Question

_______ the boy was walking down the street, the UFO landed.

A. While B. After C .Before D. until

 

Answer 1

A

【解析】

试题分析：句意：当这位男孩在街道上散步时，UFO着陆。While当……的时候；after在···……之后；before在……之前；until直到。所以选A。

考点：考查连词。