问题补充：
Leif Erickson reached North America around the year 1000, but the attempt to explore was started slowly. It would be five centuries 1 other Europeans landed on that continent.
Why were Europeans the ones to 2 to the American? The Chinese and Arabs had the 3 and technology to sail across the seas. 4 of them tool regular voyages in the Indian Ocean and the Asian Pacific for trade. But exploration? By the mid-15th century China had followed the closed-door policy to 5 itself from the rest of the world. The Arabs, with access to the minerals and spices (香料) of Africa and the Far East, saw no 6 to journey into the unknown.
Europe, on the other hand, needed gold and silver; its mines could not 7 the demand for coinage (铸币). Ottoman Turks blocked the routes across the land to Asia. Only the sea held the promise of new wealth.
8 the return of Magellan’s ships in 1522 from its voyage around the world, the belief was 9 that the oceans were interconnected, promising the age of discovery. The English, as well as the Spanish, Portuguese and French, 10 themselves to finding the “river of the west” through North America to the east.
【小题1】A．afterB．sinceC．beforeD．when【小题2】A．pushB．pullC．drawD．drive【小题3】A．sourcesB．resourcesC．substancesD．matters【小题4】A．NeitherB．BothC．AnyD．None【小题5】A．preventB．protectC．isolateD．differ【小题6】A．needB．chanceC．choiceD．regret【小题7】A．createB．meetC．raiseD．develop【小题8】A．AsB．ForC．WithD．At【小题9】A．extendedB．estimatedC．acceptedD．made【小题10】A．contributedB．referredC．devotedD．connectedC
答案：
(答案→)C
解析：
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