Question

【题目】 Exactly ______ the potato was introduced into Europe is uncertain, but it was probably around 1565.

A. whether B. why C. how D. when

Answer 1

【答案】D

【解析】

试题分析：句意：马铃薯被引入欧洲的时间不确定，但很可能是1565年。A. whether 是否；B. why 为什么；C. how 怎样；D. when什么时候。Exactly ______ the potato was introduced into Europe是主语从句，根据后面的时间可知，前面是在说时间，故选D。