Trade is certainly a main 30 force for globalization.
答案：(A) driving
driving force 是字詞搭配，意為「推動力、原動力」，本句指貿易是全球化的主要推力；pulling、riding、bringing 都不與 force 構成這個固定說法。
答對率 30%。
driving 在你腦中就是「開車」，看到 a main ___ force 時，四個 -ing 都填得下去，於是憑感覺猜。這一格考的不是文法，純粹是「知不知道 driving force 這個搭配」。
劍橋詞典把 driving force 收為獨立詞條，釋義是「促使某事發生的強大人物或事物」；Collins 的說明是「造成某事發生的主要因素」。中文就是「推動力、原動力、主要推手」。drive 這個字除了「駕駛」，更核心的意思是「驅動、推動」——drive the economy（帶動經濟）、drive change（推動改變），driving force 就是從這個意思長出來的。
前一句 Without international trade, nations would be limited to the goods and services produced within their own borders.（沒有國際貿易，各國就只能侷限於自己境內生產的商品與服務）已經把貿易的推動角色講明白；本句是承接的結論句，說貿易「確實是全球化的主要推力」。
pulling force 在物理上指「拉力」，不用來形容抽象的推動；riding force、bringing force 都不是英文的說法。搭配題沒有道理可推，只能靠平時累積。
a driving force（原動力、主要推手）、drive the economy／change（帶動經濟／推動改變）、a driving factor（推動因素）、a major force in…（…的一大力量）。
International trade is the exchange of goods and services between countries. Trade is driven by different production costs in different countries, making 26 cheaper for some countries to import goods rather than make them. A country is said to have a comparative advantage over another when it can produce a commodity more cheaply. This comparative advantage is 27 by key factors of production such as land, capital, and labor.
While international trade has long been conducted in history, its economic, social, and political importance has been 28 in recent centuries. During the 1990s, international trade grew by nearly 8.6 each year. In the year 1990 alone, the growth in trade in services was as high as 19. Today, all countries are involved in, and to varying degrees dependent on, trade with other countries.
29 international trade, nations would be limited to the goods and services produced within their own borders. Trade is certainly a main 30 force for globalization. It is also the subject of many international agreements that aim to govern and facilitate international trade, such as those negotiated through the World Trade Organization (WTO).