He was about to go out for a walk _____ it begin to rain.a.when b_英语解答

He was about to go out for a walk _____ it begin to rain.
a.when b.while c.as
选B 为什么?A.C 为何不可

人气：142 ℃　时间：2020-01-29 05:41:39

解答

答案是B
固定巨型：be about to do sth when +句子,这是 when 的最典型用法