點揭模式：空白處點一下就顯示該格答案，再點可藏起。適合投影提問。Click mode: tap a blank to reveal that answer; tap again to hide it. Useful when projecting questions.
畫筆已開：可在筆記任何位置書寫。關閉畫筆後才可捲動、放大、點揭或開連結。筆跡會跟住文字，放大縮小都不會走位。寫完請按「分享」，在 iPad 選郵件寄出。Pen is on: write anywhere on the notes. Turn the pen off to scroll, pinch-zoom, tap blanks, or open links. Ink stays glued to the text when you zoom. When finished, tap Share and choose Mail on iPad.
HTMS 經濟科課堂筆記 | 編輯：Mr. Sam Wong | 重要聲明：本課堂筆記僅供已購買課本之學生使用，並僅限內部參考。HTMS Economics Lesson Notes | Editor: Mr. Sam Wong
Important: These lesson notes are intended only for students who have purchased the textbook and are for internal use only.
對齊課堂筆記 511／第 11 章（11.1–11.6）。11.1A 只辨認貿易障礙；關稅／配額如何改變價格與進口量見後續章。生產可能線（PPF）不在本章範圍。匯率見 513。 Aligned with class notes 511 / Chapter 11 (sections 11.1–11.6). Section 11.1A only identifies trade barriers; how tariffs and quotas change price and import quantity is in a later chapter. Illustration by the production possibilities frontier is not required. The exchange rate is in 513.
讀完本章，應能：
After this chapter you should be able to:
國際貿易是指跨越國界和地域的貨品和服務的交易。
International trade refers to the exchange of goods and services between different countries or regions.
自由貿易是指不受任何政府措施限制的國際貿易。
Free trade is international trade that is NOT hindered by any restrictions imposed by the government.
會與其他國家進行貿易活動的經濟體系。
An economy that would engage in trading activities with other countries.
自給自足、不與其他國家進行貿易的經濟體系。
An economy that is self-sufficient and would NOT engage in trading activities with other countries.
貿易障礙是政府用來限制國際貿易的措施。有貿易障礙，就不是自由貿易。
Trade barriers are restrictions imposed by the government that hinder international trade. If there are trade barriers, the trade is not free trade.
對進口貨品徵收的稅。進口商要多付一筆錢才能把貨品運入本地市場。
A tax on imports. Importers must pay extra to bring the good into the domestic market.
限制進口的數量。超過上限的貨物不准進口（或要另申請）。
A limit on the quantity of imports. Goods above the ceiling are not allowed in (or need extra permission).
其他常見例子還包括進口附加費、禁止進口某些貨品等。本章其餘例子假設沒有貿易障礙。關稅和配額如何改變價格與進口量，見後續章。
Other examples include an import surcharge and a ban on certain imports. The rest of this chapter assumes no trade barriers. How a tariff or a quota changes the price and the quantity of imports is in a later chapter.
貿易障礙：政府的限制（關稅、配額、附加費）。沒有政府出手，就不是貿易障礙。
Trade barrier: a government restriction (tariff, quota, surcharge). If the government does not impose it, it is not a trade barrier.
運費／交易費用：把貨品由一國運到另一國的成本。11.5 會用來扣減貿易得益，但它不是政府措施。
Transport / transaction cost: the cost of moving goods from one country to another. Section 11.5 subtracts it from the gain from trade, but it is not a government restriction.
樂澄的社想保護自己的凍飲攤。若學生會規定：校外買入的每杯凍飲要多繳 $2，這像關稅。若規定全日最多只准帶入 20 杯外面的凍飲，這像配額。專線小巴把貨運到校門的車資則是運費，不是貿易障礙。
Chloe’s house wants to protect its drink stall. If the student union charges $2 on every drink brought in from outside, that is like a tariff. If it allows at most 20 outside drinks a day, that is like a quota. The minibus fare to carry the drinks to the gate is transport cost, not a trade barrier.
小練習 11.1A 哪項是貿易障礙？Quick check 11.1A Which is a trade barrier?
下列哪一項是貿易障礙？
A. 由內地運米來港的船運費
B. 政府對進口大米徵收關稅
C. 兩國生產大米的機會成本不同
D. 入口國的機會成本高於貿易比率
Which of the following is a trade barrier?
A. the shipping cost of rice from the Mainland to Hong Kong
B. a tariff imposed by the government on imported rice
C. different opportunity costs of producing rice in the two countries
D. the importing country’s opportunity cost being higher than the terms of trade
答案：B
Answer: B
只有政府對進口徵稅才是貿易障礙。A 是運費；C、D 是比較優勢與貿易得益，不是政府限制。
Only a government tax on imports is a trade barrier. A is transport cost; C and D are comparative advantage and the gain from trade, not a government restriction.
樂澄的學校飯堂可以蒸飯、炒餸，但不能自己種米。香港同樣缺乏耕地與能源，許多食品和原料要進口；同時把金融、運輸等服務出口。這不是「喜歡進口」，而是資源組合決定不能樣樣自給。
Chloe’s school canteen can steam rice and cook dishes, but it cannot grow rice. Hong Kong likewise lacks farmland and energy, so many foods and materials are imported, while financial and transport services are exported. This is not a taste for imports; the resource mix makes self-sufficiency impossible.
解釋為何各貿易國能從國際貿易中獲益，以及國際貿易如何運作前，有以下假設：
There are three assumptions in the examples discussed in this chapter:
題目通常以下表呈現：每單位資源的產量。
According to the above assumptions, the situation is usually presented as units of each good produced per unit of resources.
| 食物 (F)Food (F) | 成衣 (C)Clothing (C) | ||
|---|---|---|---|
| 甲國Country A | 8 | 或or | 10 |
| 乙國Country B | 2 | 或or | 8 |
「或」表示同一單位資源只能生產其中一種物品，不是同時生產兩種。
The “or” means one unit of resources can produce one good or the other, not both at once.
以同等數量的資源，所生產的物品比另一國多；或以較少數量的資源，能生產相同數量的產品。亦即生產該物品時，生產力較其他國家為高。
A country has an absolute advantage in producing a good if it can produce a larger amount of the good than the other country with the same amount of resources, or produce the same amount with fewer resources. Both imply higher productivity in that good.
絕對劣勢：以同等數量的資源，所生產的物品比另一國少；或以較多資源生產相同數量。生產力較其他國家為低。
The opposite of absolute advantage is absolute disadvantage: smaller output with the same resources, or more resources for the same output — lower productivity.
正確：先問兩國投入的資源是否相同。資源相同，才可用最高產量直接比；資源表則比「生產 1 單位所需資源較少」的一方。
Correct: first ask whether the two countries use the same amount of resources. Only then may you compare maximum output. On a resource table, the country that needs fewer resources per unit has the absolute advantage.
易錯：看見甲國最高產量較大就寫「甲國有絕對優勢」——若甲國資源是乙國的兩倍，較大總產量仍可能是較低生產力。
Trap: writing that Country A has an absolute advantage just because its maximum output is larger — if A has twice the resources, a larger total can still mean lower productivity.
下表顯示兩國每 1 工時所生產的物品 X：
The following table shows the units of food and clothing produced per unit of labour.
| 每 1 工時的物品 X | |
|---|---|
| 甲國 | 5 單位 |
| 乙國 | 2 單位 |
| Food (F) per unit of labour | Clothing (C) per unit of labour | |
|---|---|---|
| Country A | 8 units | 10 units |
| Country B | 2 units | 8 units |
甲國有生產物品 X 的絕對優勢，因為甲國能以相同的資源（1 工時），生產較多數量的 X。
Country A has an absolute advantage in producing both food and clothing, because it can produce more of each good than Country B with the same amount of resources (labour).
| 生產 1 單位 X 所需工時 | |
|---|---|
| 甲國 | 3 工時 |
| 乙國 | 8 工時 |
| Resources required for 1 unit of food | Resources required for 1 unit of clothing | |
|---|---|---|
| Country A | 5 units | 10 units |
| Country B | 8 units | 2 units |
甲國有生產物品 X 的絕對優勢，因為甲國能以較少的資源（3 工時），生產同等數量的 X。
Country A has an absolute advantage in food (fewer resources per unit). Country B has an absolute advantage in clothing.
國與國之間比較，有可能一個國家在所有物品的生產上擁有絕對優勢，也可能全部物品均有絕對劣勢。
It is possible for a country to have absolute advantages in producing both products.
樂澄一小時可包 8 個飯團或調 10 杯凍飲；文諾一小時可包 2 個飯團或調 8 杯凍飲。同等時間（資源）下，樂澄兩樣都較多，所以飯團和凍飲都有絕對優勢。文諾兩樣都有絕對劣勢——這不阻止稍後用比較優勢分工。
In one hour Chloe can wrap 8 rice rolls or mix 10 cold drinks; Marcus can wrap 2 rice rolls or mix 8 drinks. With the same time, Chloe produces more of both, so she has an absolute advantage in both. Marcus has an absolute disadvantage in both — that will not stop later specialization by comparative advantage.
小練習 11.2A 成衣與蘋果Quick check 11.2A Garments and apples
下表顯示兩個國家以相同資源所能生產的成衣和蘋果數量：甲國 20 單位成衣或 30 單位蘋果；乙國 30 單位成衣或 40 單位蘋果。試分析兩國的絕對優勢和絕對劣勢。
With the same resources, Country A can produce 20 garments or 30 apples; Country B can produce 30 garments or 40 apples. Who has the absolute advantage?
答案：乙國生產成衣及蘋果都有絕對優勢，甲國生產成衣及蘋果都有絕對劣勢。因為乙國以同等數量的資源，生產的成衣和蘋果均較甲國多。
Answer: Country B has an absolute advantage in both garments and apples; Country A has an absolute disadvantage in both, because B produces more of each good with the same resources.
公開試題 HKCEE 2004 卷一 題 11(a)(i)Public Exam HKCEE 2004 Paper 1 Q11(a)(i)
假設甲經濟的資源是香港的兩倍。兩個經濟都使用全部資源來生產。甲經濟全年最高產量：衣服 20 單位或汽車 10 單位；香港：衣服 12 單位或汽車 3 單位。解釋甲經濟生產衣服是否享有絕對優勢。
Suppose the amount of resources of Economy A is double that of Hong Kong and both economies use ALL their resources in production. Maximum output in a year: Economy A 20 clothing or 10 cars; Hong Kong 12 clothing or 3 cars. Explain whether Economy A has an absolute advantage in producing clothing.
答案：否。同等資源下，甲經濟生產衣服的數量較香港少（甲用一半資源等同香港全部資源時，衣服為 10 單位，香港為 12 單位），故甲經濟生產衣服的生產力較低，沒有絕對優勢。
Answer: No. With the same amount of resources, Economy A produces a smaller amount of clothing than Hong Kong (10 versus 12). Economy A has a lower productivity than HK in producing clothing.
公開試題 HKCEE 2002 卷一 題 9(a)Public Exam HKCEE 2002 Paper 1 Q9(a)
下表顯示甲國與乙國各自在一年內使用國內全部資源所能生產玩具及電腦的最高產量。甲國：玩具 15 或電腦 5；乙國：玩具 10 或電腦 5。解釋我們可否得出：甲國在生產玩具方面享有絕對優勢。
The table shows the maximum amount of toys and computers that Country A and Country B can produce in a year with ALL of their resources. A: 15 toys or 5 computers; B: 10 toys or 5 computers. Explain whether we can conclude that Country A has an absolute advantage in producing toys.
答案：不可以。由於不知道兩國「使用國內全部資源」的數量是多少，因此不能確定甲國在生產玩具是否擁有絕對優勢。
Answer: We cannot, because the amount of resources of both countries is not given.
比較優勢：生產某物品的機會成本較其他國家低。
A country has a comparative advantage in producing a good if it can produce the good at a lower opportunity cost than the other country.
比較劣勢：生產某物品的機會成本較其他國家高。
The opposite of comparative advantage is comparative disadvantage: a higher opportunity cost.
生產 1 單位物品 X 的機會成本 = 生產 Y 的數量／生產 X 的數量。
Opportunity cost of producing 1F (in terms of clothing) = units of C / units of F.
| 食物 (F)Food (F) | 成衣 (C)Clothing (C) | ||
|---|---|---|---|
| 甲國Country A | 8 | 或or | 10 |
| 乙國Country B | 2 | 或or | 8 |
在甲國，用 1 單位勞工生產 8F，就不能用同一單位勞工生產 10C。因此生產 1F 的機會成本 = 10C／8 = 1.25C。
In Country A, to employ a unit of labour to produce 8F, it CANNOT use the same unit of labour to produce 10C. Opportunity cost of producing 1F = 10C／8 = 1.25C.
| 生產 1 單位的機會成本Opportunity cost of producing one unit of | ||
|---|---|---|
| 食物 (F)Food (F) | 成衣 (C)Clothing (C) | |
| 甲國Country A | 1.25C | 0.8F |
| 乙國Country B | 4C | 0.25F |
乙國生產食物的機會成本較低，食物有比較優勢；甲國生產成衣的機會成本較低，成衣有比較優勢。
Country B has a comparative advantage in food because it can produce food at a lower opportunity cost. Country A has a comparative advantage in clothing.
生產 1 單位物品 X 的機會成本 = 生產 1 單位 X 所需的資源數量／生產 1 單位 Y 所需的資源數量。
If 2 units of labour produce 1F, those 2 units could have produced (2／4) = 0.5C. Opportunity cost of 1F = labour for F／labour for C.
| 生產 1 單位所需勞工Labour required per unit | ||
|---|---|---|
| 食物 (F)Food (F) | 成衣 (C)Clothing (C) | |
| 甲國Country A | 2 | 4 |
| 乙國Country B | 4 | 6 |
| 生產 1 單位的機會成本Opportunity cost of producing one unit of | ||
|---|---|---|
| F | C | |
| 甲國Country A | 0.5C | 2F |
| 乙國Country B | 0.67C | 1.5F |
甲國生產食物有比較優勢；乙國生產成衣有比較優勢。
Country A has a comparative advantage in food; Country B has a comparative advantage in clothing.
一個國家在生產某物品具有比較優勢時，即表示此國家在另一物品上必然有比較劣勢。當兩國生產某物品的機會成本相同時，兩國不存在比較優勢或劣勢。
It is impossible for a country to have comparative advantages in producing both products. If opportunity costs are the same, neither country has a comparative advantage.
絕對優勢：要比較同等資源下的產量。只給「全部資源的最高產量」、沒有資源總量，不能斷定絕對優勢。
Absolute advantage: you must compare output with the same resources. A maximum-output table without the resource totals is not enough.
比較優勢：機會成本是兩種物品最高產量的比率，不必知道資源總量，可以斷定。
Comparative advantage: opportunity cost is the ratio of the two maximum outputs, so you can conclude even when resource totals are missing.
樂澄 1 小時：8 飯團或 10 凍飲。文諾 1 小時：2 飯團或 8 凍飲。樂澄 1 個飯團的機會成本是 10／8 = 1.25 杯凍飲；文諾是 8／2 = 4 杯。樂澄生產飯團的機會成本較低，飯團有比較優勢；文諾調凍飲的機會成本較低（2／8 = 0.25 個飯團，對比樂澄 8／10 = 0.8 個），凍飲有比較優勢。
Chloe: 8 rolls or 10 drinks per hour. Marcus: 2 rolls or 8 drinks. Chloe’s opportunity cost of 1 roll is 1.25 drinks; Marcus’s is 4 drinks. Chloe has a comparative advantage in rolls; Marcus has a comparative advantage in drinks (0.25 rolls vs Chloe’s 0.8).
小練習 11.3A 成衣與蘋果的機會成本Quick check 11.3A Opportunity cost of garments and apples
甲國：20 成衣或 30 蘋果；乙國：30 成衣或 40 蘋果。分析比較優勢。
Country A: 20 garments or 30 apples; Country B: 30 garments or 40 apples. Who has the comparative advantage in each good?
答案：甲國 1 成衣 = 30／20 = 1.5 蘋果；1 蘋果 = 20／30 ≈ 0.67 成衣。
乙國 1 成衣 = 40／30 ≈ 1.33 蘋果；1 蘋果 = 30／40 = 0.75 成衣。
乙國成衣機會成本較低（1.33 < 1.5），成衣有比較優勢；甲國蘋果機會成本較低（0.67 < 0.75），蘋果有比較優勢。
Answer: Country A: 1 garment = 30／20 = 1.5 apples; 1 apple = 20／30 ≈ 0.67 garments.
Country B: 1 garment = 40／30 ≈ 1.33 apples; 1 apple = 30／40 = 0.75 garments.
B’s garment cost is lower (1.33 < 1.5), so B has CA in garments; A’s apple cost is lower (0.67 < 0.75), so A has CA in apples.
小練習 11.3B 電子錶與計算機Quick check 11.3B Watches and calculators
每單位產出所需資源：新加坡電子錶 10 或計算機 6；香港電子錶 8 或計算機 12。
Resources required per unit: Singapore 10 (watch) or 6 (calculator); Hong Kong 8 (watch) or 12 (calculator).
答案：(a) 電子錶：香港 8 < 新加坡 10；計算機：新加坡 6 < 香港 12。香港電子錶有絕對優勢，新加坡計算機有絕對優勢。
(b) 新加坡 1 電子錶 = 10／6 ≈ 1.66 單位計算機；香港 1 電子錶 = 8／12 ≈ 0.66 單位計算機。
(c) 香港機會成本較低（0.66 < 1.66），電子錶有比較優勢。
Answer: (a) Watches: Hong Kong 8 < Singapore 10; calculators: Singapore 6 < Hong Kong 12. Hong Kong has an absolute advantage in watches; Singapore has an absolute advantage in calculators.
(b) Singapore: 1 watch = 10／6 ≈ 1.66 calculators; Hong Kong: 1 watch = 8／12 ≈ 0.66 calculators.
(c) Hong Kong’s cost is lower (0.66 < 1.66), so it has CA in watches.
公開試題 HKCEE 2002 卷一 題 9(b)Public Exam HKCEE 2002 Paper 1 Q9(b)
同上表（甲國玩具 15 或電腦 5；乙國玩具 10 或電腦 5）。解釋我們可否得出：甲國在生產玩具方面享有比較優勢。
Same table (A: 15 toys or 5 computers; B: 10 toys or 5 computers). Explain whether we can conclude that Country A has a comparative advantage in producing toys.
答案：可以。甲國 1 單位玩具的機會成本是 1／3 單位電腦；乙國是 1／2 單位電腦。甲國機會成本較低，玩具有比較優勢。
Answer: Yes. In Country A the cost of 1 toy is 1／3 computer; in Country B it is 1／2 computer. Country A has a lower cost in producing toys.
小練習 11.3C 選擇Quick check 11.3C MC
設某國生產物品 X 享有絕對優勢。下列哪一項是正確的？（1994）
A. 該國生產物品 X 有可能較另一國家的機會成本高
B. 用同等數量的資源，該國生產物品 X 的數量可比生產另一物品為多
C. 該國生產物品 X 也會享有比較優勢
D. 該國生產另一物品會有絕對劣勢
If a country has an absolute advantage in X, which is correct?
A. Its opportunity cost of X may be higher than the other country’s
B. With the same resources it must produce more X than of the other good
C. It must also have a comparative advantage in X
D. It must have an absolute disadvantage in the other good
答案：A
Answer: A
絕對優勢比生產力；比較優勢比機會成本。生產力較高的一方，機會成本仍可能較高。
Absolute advantage is productivity; comparative advantage is opportunity cost. The more productive country can still have the higher opportunity cost.
假設只有物品 X 和物品 Y。若某國生產物品 X 有比較優勢，它生產物品 Y（2000）
A. 會有絕對優勢 B. 會有絕對劣勢 C. 也會有比較優勢 D. 的機會成本較高
If a country has a comparative advantage in X (only two goods), then for Y:
A. it has an absolute advantage B. it has an absolute disadvantage C. it also has a comparative advantage D. its opportunity cost is higher
答案：D
Answer: D
如果兩國各自專門生產機會成本較低（具有比較優勢）的物品，兩國總產量會增加。兩國進行貿易分享增加的產出而互惠得益。
The principle of comparative advantage states that if each country specializes in the production of the good in which it has a lower opportunity cost, the total output of all countries will increase.
這意味着：即使一國在兩種物品都有絕對優勢，仍可能願意與有絕對劣勢的國家貿易，因為雙方都可以享受更多產出。
The principle implies that a country with an absolute advantage in producing a good may still be willing to trade with a country with an absolute disadvantage because it is possible for both of them to enjoy more output.
下表顯示兩國各自使用 1 單位資源所能生產電腦及成衣的產量。注意甲國在兩種物品都有絕對優勢。
The following table shows the units of computer and garment produced per unit of labour. Country A has the absolute advantage in producing BOTH goods.
| 電腦 (C)Computer (C) | 成衣 (G)Garment (G) | ||
|---|---|---|---|
| 甲國Country A | 8 | 或or | 10 |
| 乙國Country B | 2 | 或or | 8 |
假設兩國分別擁有 10 單位資源。專門化之前，將 7 單位資源生產電腦、3 單位生產成衣。
Suppose each country has 10 units of labour and both allocate 7 units to computers and 3 units to garments before specialization.
| 專門化之前Before specialization | C | G | |
|---|---|---|---|
| 甲國Country A | 56 | 及AND | 30 |
| 乙國Country B | 14 | 及AND | 24 |
| 總產量World output | 70 | 及AND | 54 |
生產 1 單位電腦的機會成本：甲國 1.25G；乙國 4G。甲國機會成本較低，應專門生產電腦。
Opportunity cost of a computer: Country A 1.25G; Country B 4G. Country A should specialize in computers.
生產 1 單位成衣的機會成本：甲國 0.8C；乙國 0.25C。乙國機會成本較低，應專門生產成衣。
Opportunity cost of a garment: Country A 0.8C; Country B 0.25C. Country B should specialize in garments.
| 專門化之後After specialization | C | G | |
|---|---|---|---|
| 甲國Country A | 80 | 及AND | 0 |
| 乙國Country B | 0 | 及AND | 80 |
| 總產量World output | 80 | 及AND | 80 |
| C | G | |
|---|---|---|
| 分工前總產量Without specialization | 70 | 54 |
| 分工後總產量With specialization | 80 | 80 |
| 增加產量Increase in output | 10 | 26 |
分工後總產量增加，符合比較優勢法則。生產某物品的機會成本較其他國家低，將會是該物品的出口國；機會成本較高，將會是該物品的入口國。
Total world output increases after specialization, which is consistent with the principle. The country with the lower opportunity cost will be the exporting country of that good; the country with the higher opportunity cost will be the importing country.
正確：若各國專門生產（specializes in）機會成本較低的物品，所有國家的總產量會增加。單寫「生產」而不寫專門化，公開試不給該分。
Correct: if each country specializes in the good with the lower opportunity cost, total output of all countries will increase. “Produces” without specialization is not accepted.
易錯：寫成「有絕對優勢的國家出口該物品」——法則看的是機會成本，不是絕對優勢。
Trap: writing that the country with an absolute advantage exports the good — the principle looks at opportunity cost, not absolute advantage.
公開試題 HKCEE 2005 卷一 題 10(b)(i)Public Exam HKCEE 2005 Paper 1 Q10(b)(i)
同等資源下，甲國手錶 10 或電視 5；乙國手錶 20 或電視 15。說出比較優勢法則。根據此法則，解釋哪一國出口手錶。
With the same resources: Country A 10 watches or 5 TV sets; Country B 20 watches or 15 TV sets. State the principle of comparative advantage. According to this principle, explain which country would export watches.
答案：若各國專門生產機會成本較低的物品，所有國家的總產量會增加。甲國 1 對手錶的機會成本是 0.5 部電視；乙國是 0.75 部電視。甲國機會成本較低，應生產並出口手錶。
Answer: If each country specializes in the good with a lower opportunity cost, the total output of all countries will increase. Country A: 1 watch costs 0.5 TV; Country B: 0.75 TV. Country A should produce and export watches.
貿易比率是指進口 1 單位物品所需的出口物品數量，或出口 1 單位物品所需的進口物品數量，亦代表一個國家選擇透過貿易而非自行生產去獲得某物品的機會成本。因此，貿易比率是該物品的國際價格。
Terms of trade refers to the amount of goods that a country must export to get one unit of import. It represents the opportunity cost of obtaining goods through trade rather than producing them within the country. It is the exchange ratio, or the import／export price of a good in trade.
表達方式：各國可以 2 單位成衣換 1 單位食物，即 1F = 2C。
Presented as 1F = 2C: the countries exchange 2 units of clothing for 1 unit of food, or vice versa.
當入口物品的貿易比率（入口價）小於本地生產的機會成本（本地價格），入口國有貿易得益。
It would gain when the opportunity cost of obtaining a good from trade is lower than that of producing the good with its own resources.
當出口物品的貿易比率（出口價）大於本地生產的機會成本（本地價格），出口國有貿易得益。
It would gain when the price of a good it can sell for is higher than the opportunity cost of its production.
小練習 11.5A 入口／出口食物Practice 11.4.1 Importing / exporting food
在丙國，生產 1 單位食物的機會成本是 2 單位成衣。以下貿易比率，丙國能否從入口食物而得益？1F = 1.2C；1F = 3C；2F = 3C；3F = 6C；1C = 0.8F。
In Country H, the opportunity cost of producing 1 unit of food is 2 units of clothing. Will the country gain from importing food if the terms of trade is: 1F = 1.2C; 1F = 3C; 2F = 3C; 3F = 6C; 1C = 0.8F?
答案：入口價須 < 2C。
Answer: import price must be < 2C.
| 貿易比率Terms of trade | 換成 1FAs 1F | 對比 2Cvs 2C | 入口得益？Gain from import? |
|---|---|---|---|
| 1F = 1.2C | 1.2C | < 2C | 得益gain |
| 1F = 3C | 3C | > 2C | 不得益no |
| 2F = 3C | 1.5C | < 2C | 得益gain |
| 3F = 6C | 2C | = 2C | 不得益（等於本地成本）no (equal to domestic cost) |
| 1C = 0.8F | 1.25C | < 2C | 得益gain |
在丁國，生產 1 單位食物的機會成本是 1.5 單位成衣。丁國出口食物：1F = 1.2C；1F = 3C；2F = 3C；3F = 6C；1C = 0.8F。
In Country K, the opportunity cost of producing 1 unit of food is 1.5 units of clothing. Will it gain from exporting food?
答案：出口價須 > 1.5C。
Answer: export price must be > 1.5C.
| 貿易比率Terms of trade | 換成 1FAs 1F | 對比 1.5Cvs 1.5C | 出口得益？Gain from export? |
|---|---|---|---|
| 1F = 1.2C | 1.2C | < 1.5C | 不得益no |
| 1F = 3C | 3C | > 1.5C | 得益gain |
| 2F = 3C | 1.5C | = 1.5C | 不得益no |
| 3F = 6C | 2C | > 1.5C | 得益gain |
| 1C = 0.8F | 1.25C | < 1.5C | 不得益no |
貿易比率互惠，是指貿易雙方都能從貿易中得益。若不是互惠，通常國家不會貿易。兩國是否進行貿易，視乎貿易比率而定。
Terms of trade is mutually beneficial when both countries involved in trade can gain from trading. If it is NOT mutually beneficial, usually countries will NOT trade.
假設甲、乙兩國分別生產蔬菜 (P) 及手機 (M) 的機會成本：
The following table shows the units of pineapples and mobile phones produced per unit of labour. The opportunity costs are:
| 蔬菜 (P)Pineapples (P) | 手機 (M)Mobile phone (M) | ||
|---|---|---|---|
| 甲國 | 0.5M | 或 | 2P |
| 乙國 | 0.625M | 或 | 1.6P |
| Country A | 1／2 M | or | 2P |
| Country B | 5／8 M | or | 1.6P |
根據比較優勢法則，甲國出口蔬菜、入口手機；乙國出口手機、入口蔬菜。
Country A should specialize in pineapples (lower opportunity cost) and Country B in mobile phones. A exports pineapples and imports phones; B exports phones and imports pineapples.
| 蔬菜的進／出口P importer / exporter | 本地機會成本Domestic OC | 交易 1P 有利的貿易比率Gain on 1P only if exchanged for | |
|---|---|---|---|
| 甲國Country A | 出口國Exporter | 1P = 0.5M | > 0.5M |
| 乙國Country B | 入口國Importer | 1P = 0.625M | < 0.625M |
交易 1 單位蔬菜的互惠貿易比率範圍是 0.5M < 1P < 0.625M。
The mutually beneficial terms of trade of pineapples: 0.5M < 1P < 0.625M (or 1／2 M < 1P < 5／8 M).
| 手機的進／出口M importer / exporter | 本地機會成本Domestic OC | 交易 1M 有利的貿易比率Gain on 1M only if exchanged for | |
|---|---|---|---|
| 甲國Country A | 入口國Importer | 1M = 2P | < 2P |
| 乙國Country B | 出口國Exporter | 1M = 1.6P | > 1.6P |
交易 1 單位手機的互惠貿易比率範圍是 1.6P < 1M < 2P。
The mutually beneficial terms of trade of mobile phones: 1.6P < 1M < 2P.
正確：較低機會成本 < 1 單位該物品 < 較高機會成本。端點上，其中一國貿易得益為零，通常不視為互惠。
Correct: lower OC < 1 unit of the good < higher OC. At an endpoint one country’s gain is zero, so it is not mutually beneficial.
易錯：寫成 ≥ 或 ≤，或把 1P = 0.5M 算進互惠範圍。
Trap: writing ≥ or ≤, or counting 1P = 0.5M as mutually beneficial.
家欣自己做 1 份筆記的機會成本是 2 張海報；梓軒做 1 份筆記的機會成本是 1.6 張海報。若社聯規定 1 份筆記換 1.7 張海報，家欣入口筆記划算（2 > 1.7），梓軒出口筆記划算（1.7 > 1.6）。若改成 1 份筆記換 2 張海報，家欣沒有得益，不會買。
Eslyn’s cost of 1 set of notes is 2 posters; Tsz Hin’s is 1.6 posters. If the union rate is 1 set = 1.7 posters, Eslyn gains as importer (2 > 1.7) and Tsz Hin gains as exporter (1.7 > 1.6). At 1 set = 2 posters Eslyn’s gain is zero, so she will not buy.
小練習 11.5B 哪些是互惠比率？Practice 11.4.2–11.4.3 Which TOT is mutually beneficial?
蔬菜：1P = 0.45M ／ 1P = 0.5M ／ 1P = 0.55M ／ 2P = 1.3M ／ 1M = 1.7P
Pineapples: 1P = 0.45M; 1P = 0.5M; 1P = 0.55M; 2P = 1.3M; 1M = 1.7P
答案：互惠範圍是 0.5M < 1P < 0.625M。
Answer: the mutually beneficial range is 0.5M < 1P < 0.625M.
| 貿易比率Terms of trade | 換成 1PAs 1P | 對比範圍vs the range | 互惠？Mutually beneficial? |
|---|---|---|---|
| 1P = 0.45M | 0.45M | < 0.5M（低於甲國成本）< 0.5M (below A’s cost) | 否no |
| 1P = 0.5M | 0.5M | = 0.5M（端點）= 0.5M (endpoint) | 否no |
| 1P = 0.55M | 0.55M | 在範圍內inside the range | 是yes |
| 2P = 1.3M | 0.65M | > 0.625M（高於乙國成本）> 0.625M (above B’s cost) | 否no |
| 1M = 1.7P | ≈ 0.59M | 在範圍內inside the range | 是yes |
手機：1M = 1.5P ／ 1M = 1.6P ／ 1M = 1.8P ／ 5M = 8.5P ／ 1P = 0.4M
Phones: 1M = 1.5P; 1M = 1.6P; 1M = 1.8P; 5M = 8.5P; 1P = 0.4M
答案：互惠範圍是 1.6P < 1M < 2P。
Answer: the mutually beneficial range is 1.6P < 1M < 2P.
| 貿易比率Terms of trade | 換成 1MAs 1M | 對比範圍vs the range | 互惠？Mutually beneficial? |
|---|---|---|---|
| 1M = 1.5P | 1.5P | < 1.6P（低於乙國成本）< 1.6P (below B’s cost) | 否no |
| 1M = 1.6P | 1.6P | = 1.6P（端點）= 1.6P (endpoint) | 否no |
| 1M = 1.8P | 1.8P | 在範圍內inside the range | 是yes |
| 5M = 8.5P | 1.7P | 在範圍內inside the range | 是yes |
| 1P = 0.4M | 2.5P | > 2P（高於甲國成本）> 2P (above A’s cost) | 否no |
出口國的每單位出口物品貿易得益 ＝ 貿易比率 － 出口國的機會成本。入口國的每單位入口物品貿易得益 ＝ 入口國的機會成本 － 貿易比率。計算時通常以 1 單位入口或 1 單位出口物品為基準。
Gain per unit imported = importer’s domestic opportunity cost − terms of trade. Gain per unit exported = terms of trade − exporter’s domestic opportunity cost.
假設貿易比率是 1M = 1.7P：
Suppose the terms of trade is 1M = 1.7P:
| 甲國（入口國）入口 1 單位手機Country A (importer) for 1 mobile phone | |
|---|---|
| 本地機會成本（本地價格）Domestic opportunity cost | 2P |
| 減：貿易比率（國際價格）Less: terms of trade (import price) | 1.7P |
| 貿易得益Gain from trade | 0.3P |
| 乙國（出口國）出口 1 單位手機Country B (exporter) for 1 mobile phone | |
|---|---|
| 貿易比率（國際價格）Terms of trade (export price) | 1.7P |
| 減：本地機會成本Less: domestic opportunity cost | 1.6P |
| 貿易得益Gain from trade | 0.1P |
兩國貿易總得益 = 兩國機會成本的差額 = 0.3P + 0.1P = 0.4P（即 2P − 1.6P）。怎樣分配貿易得益，取決於貿易比率落在範圍內的哪一點。
Total gain of the world = 0.3P + 0.1P = 0.4P, which equals the difference between the two domestic opportunity costs (2P − 1.6P). How the gain is shared depends on where the terms of trade sit inside the range.
小練習 11.5C 計算貿易得益Practice 11.4.4 Calculate the gain
1M = 1.8P：甲國 2P − 1.8P = 0.2P；乙國 1.8P − 1.6P = 0.2P。
1M = 1.8P: Country A 2P − 1.8P = 0.2P; Country B 1.8P − 1.6P = 0.2P.
1M = 2P：甲國 0；乙國 0.4P。甲國不得益，不是互惠。
1M = 2P: Country A 0; Country B 0.4P. A does not gain — not mutually beneficial.
1P = 0.6M（即 1M ≈ 1.67P）：甲國約 0.33P；乙國約 0.07P。
1P = 0.6M (1M ≈ 1.67P): Country A about 0.33P; Country B about 0.07P.
公開試題 HKCEE 2005 卷二 題 46Public Exam HKCEE 2005 Paper 2 Q46
甲國生產 1 單位玩具需 1 工時、1 單位手錶需 3 工時；乙國玩具 2 工時、手錶 4 工時。根據比較優勢原理，甲國會出口 ______ 和進口 ______，而一個令兩國皆得益的交易比率可以是 1 單位玩具等於 ______。
A. 玩具…手錶…0.4 單位手錶 B. 玩具…手錶…2.5 單位手錶 C. 手錶…玩具…0.4 單位手錶 D. 手錶…玩具…2.5 單位手錶
Man-hours: A 1 (toy), 3 (watch); B 2 (toy), 4 (watch). Country A will export _______ and import _______, and a mutually beneficial terms of trade can be 1 unit of toys equals _______.
A. toys … watches … 0.4 units of watches B. toys … watches … 2.5 units of watches C. watches … toys … 0.4 units of watches D. watches … toys … 2.5 units of watches
答案：A
Answer: A
甲國 1 玩具 = 1／3 手錶；乙國 1 玩具 = 1／2 手錶。甲國出口玩具。互惠：1／3 < 1 玩具 < 1／2 手錶，0.4 在範圍內；2.5 遠高於雙方成本。
A: 1 toy = 1／3 watch; B: 1 toy = 1／2 watch. A exports toys. Mutually beneficial: 1／3 < 1 toy < 1／2 watch. 0.4 is inside; 2.5 is not.
公開試題 HKCEE 2002 卷二 題 45Public Exam HKCEE 2002 Paper 2 Q45
每單位資源：甲國 1X 或 3Y；乙國 2X 或 4Y。下列哪項貿易比率可使兩國從貿易中互利？
A. 1X = 2Y B. 1X = 3Y C. 2X = 5Y D. 以上答案皆正確
Output per unit of resources: A 1X or 3Y; B 2X or 4Y. Which terms of trade is / are mutually beneficial?
A. 1X = 2Y B. 1X = 3Y C. 2X = 5Y D. All of the above
答案：C
Answer: C
甲國 1X = 3Y，乙國 1X = 2Y。乙國出口 X。互惠：2Y < 1X < 3Y。A 與 B 是端點；C：2X = 5Y → 1X = 2.5Y，在範圍內。
A: 1X = 3Y; B: 1X = 2Y. B exports X. Mutually beneficial: 2Y < 1X < 3Y. A and B are endpoints; C means 1X = 2.5Y, inside the range.
公開試題 HKCEE 2001 卷二 題 42Public Exam HKCEE 2001 Paper 2 Q42
甲國生產 1 單位食物的機會成本是 3 單位成衣。當甲國與乙國通商時，它每出口 0.2 單位食物便可換取 1 單位進口成衣。若甲國出口 10 單位食物往乙國，則甲國的貿易總得益是
A. 20 單位的成衣 B. 30 單位的成衣減去 10 單位的食物 C. 50 單位的成衣 D. 50 單位的成衣減去 10 單位的食物
The production cost of 1 unit of food in country X is 3 units of clothing. When country X trades with country Y, it can obtain 1 unit of clothing import by export 0.2 units of food. What is country X’s total gain from trade if it exports 10 units of food?
A. 20 units of clothing B. 30 units of clothing minus 10 units of food C. 50 units of clothing D. 50 units of clothing minus 10 units of food
答案：A
Answer: A
出口 1 食物本來可在本地換 3 成衣；貿易後 1 食物換 1／0.2 = 5 成衣；每單位食物賺 2 成衣。出口 10 單位賺 20 成衣。
Domestically 1 food costs 3 clothing; through trade 1 food buys 5 clothing. Gain per unit of food exported = 2 clothing. Ten units → 20 clothing.
公開試題 HKCEE 1994 卷二 題 53Public Exam HKCEE 1994 Paper 2 Q53
一單位資源可生產：甲國時鐘 2 或玩具 4；乙國時鐘 6 或玩具 8。若貿易時 1 單位時鐘可換取 2 單位玩具，
A. 甲、乙兩國會從貿易中得益 B. 甲、乙兩國不會從貿易中得益 C. 甲國不能從貿易中得益 D. 乙國不能從貿易中得益
One unit of resources: A 2 clocks or 4 toys; B 6 clocks or 8 toys. Suppose 1 unit of clocks can be exchanged for 2 units of toys.
A. Both A and B will gain B. Both will not gain C. A will not gain D. B will not gain
答案：C
Answer: C
甲國 1 時鐘 = 2 玩具，貿易比率剛好等於甲國成本，甲國得益為零。
Country A’s cost of 1 clock is 2 toys, equal to the terms of trade, so A’s gain is zero.
若入口 1 單位手機另須支付 0.2P 運費：甲國得益由 0.3P 降至 0.1P。
If Country A pays a transportation cost of 0.2 pineapple per imported phone, its gain falls from 0.3P to 0.1P.
以 1 單位手機計算，兩國貿易總得益是 0.4P。若運輸／交易費用超過 0.4P，世界無法從貿易中得益，兩國不會貿易。蔬菜方面，上限是 0.125M。
Total gain from trading 1 mobile phone is 0.4P. If transportation／transaction cost exceeds 0.4P, it would be impossible for the world to gain. For pineapples the cap is 0.125M.
正確：當運輸成本 ≥ 兩國機會成本之差（即每單位貿易總得益），兩國皆無法從貿易中得益。
Correct: no country will gain when the transportation cost per unit ≥ the total gain from trade per unit (the difference in the two domestic opportunity costs).
易錯：把運費只從入口國的得益扣除後，忘記出口國仍可能得益；或把「大於」寫成必須「遠大於」。
Trap: subtracting transport only from the importer and ignoring that the world’s total gain is the OC gap; or requiring the cost to be “much larger” rather than ≥ the gap.
小練習 11.5D 法國與日本（紅酒／汽車）Quick check 11.5D France and Japan (wine / cars)
一單位資源：法國紅酒 4 或汽車 2；日本紅酒 1 或汽車 2。(a) 哪個國家擁有生產汽車／紅酒的比較優勢？(b) 貿易形態？(c) 以 1 單位汽車計算的互惠貿易比率？(d) 以 1 單位汽車計算的貿易總得益？(e) 貿易比率是 3 單位紅酒換 2 單位汽車，每單位出口賺多少？
Per unit of resources: France 4 wine or 2 cars; Japan 1 wine or 2 cars. Comparative advantage, pattern of trade, mutually beneficial TOT for 1 car, total gain per car, and gain per unit of export if 3 wine exchange for 2 cars.
答案：(a) 法國 1 汽車 = 2 紅酒；日本 1 汽車 = 0.5 紅酒。日本汽車有比較優勢；法國紅酒有比較優勢（法國 1 紅酒 = 0.5 汽車；日本 1 紅酒 = 2 汽車）。(b) 法國出口紅酒、入口汽車；日本出口汽車、入口紅酒。(c) 0.5 紅酒 < 1 汽車 < 2 紅酒。(d) 1.5 單位紅酒。(e) 3 紅酒換 2 汽車 → 1 紅酒換 0.66 汽車，法國每出口 1 紅酒賺 0.16 汽車；1 汽車換 1.5 紅酒，日本每出口 1 汽車賺 1 紅酒。
Answer: (a) France: 1 car = 2 wine; Japan: 1 car = 0.5 wine. Japan has CA in cars; France has CA in wine. (b) France exports wine, imports cars; Japan exports cars, imports wine. (c) 0.5 wine < 1 car < 2 wine. (d) 1.5 units of wine. (e) 3 wine for 2 cars → 1 wine = 0.66 car, France gains 0.16 car per wine exported; 1 car = 1.5 wine, Japan gains 1 wine per car exported.
公開試題 HKCEE 2000 卷一 題 11Public Exam HKCEE 2000 Paper 1 Q11
甲、乙兩國各用 40% 資源生產白酒、60% 生產衣服。實際產出：甲國白酒 1200、衣服 900；乙國白酒 400、衣服 2400。(a) 計算兩國生產一單位白酒的機會成本，並解釋哪國出口白酒。(b) 令兩國皆無法從貿易中得益的一單位白酒的最低運輸成本（以衣服單位表示）應是多少？
Each country employs 40% of resources to produce wine and 60% to produce clothing. Actual output: A 1200 wine and 900 clothing; B 400 wine and 2400 clothing. (i) Calculate the opportunity cost of one unit of wine for EACH country and explain who exports wine. (ii) What is the minimum transportation cost per unit of wine (in clothing) which will result in both countries NOT gaining from trade?
答案：(a) 全部資源時，甲國白酒 3000 或衣服 1500；乙國白酒 1000 或衣服 4000。甲國 1 白酒 = 0.5 衣服；乙國 1 白酒 = 4 衣服。甲國機會成本較低，甲國出口白酒。(b) 每單位白酒總得益 = 4 − 0.5 = 3.5 單位衣服。運輸成本 ≥ 3.5 單位衣服時，兩國皆無法得益。
Answer: (a) Full-resource output: A 3000 wine or 1500 clothing; B 1000 wine or 4000 clothing. A’s OC of wine = 0.5 clothing; B’s = 4 clothing. A has the lower OC and exports wine. (b) Total gain per unit of wine = 4 − 1／2 = 3.5 clothing. Min. transportation cost = 3.5 units of clothing.
小練習 11.5E 衣服、食米與運費Quick check 11.5E Clothing, rice and freight
每單位資源：甲國衣服 2 或食米 6；乙國衣服 6 或食米 9。1 單位衣服可交換 2 單位食米，甲國入口衣服須付運費每單位 1 食米。甲國每入口 1 單位衣服的貿易利益是多少？
Per unit of resources: A 2 clothing or 6 rice; B 6 clothing or 9 rice. 1 clothing exchanges for 2 rice, and A pays 1 rice freight per imported unit of clothing. A’s gain per unit imported?
答案：乙國衣服有比較優勢（1 衣服 = 1.5 食米，對比甲國 3 食米）。甲國入口：本地成本 3 食米，貿易比率 2 食米，運費 1 食米，得益 0 單位食米。
Answer: B has CA in clothing (1.5 rice vs A’s 3). A imports: domestic cost 3 rice − TOT 2 rice − freight 1 rice = 0.
比較優勢法則也用來說明香港出口甚麼、進口甚麼。
Using the pattern of trade in Hong Kong to illustrate the principle of comparative advantage.
欣怡暑假在機場做地勤，服務的是過境旅客——這是香港出口運輸／旅遊服務。家明在茶餐廳兼職，米、油、凍肉多是進口。同一條街，看得見的是進口食品，看不見的是出口服務，這就是有形貿易加無形貿易。
Yan’s summer job at the airport serves transit passengers — Hong Kong exporting travel / transport services. Ka Ming’s cha chaan teng job uses imported rice, oil and frozen meat. On the same street you see imported food (visible) and exported services (invisible).
小練習 11.6 香港出口甚麼？Quick check 11.6 What does Hong Kong export?
根據比較優勢，香港較可能大量出口哪一類？
A. 大米 B. 原油 C. 金融及貿易相關服務 D. 鐵礦
According to comparative advantage, Hong Kong is more likely to export:
A. rice B. crude oil C. financial and trade-related services D. iron ore
答案：C
Answer: C
香港缺乏耕地與礦產，有形出口以轉口和部分輕工為主；比較優勢在服務。
Hong Kong lacks farmland and minerals. Its comparative advantage is in services, with re-exports important in visible trade.