It was about 600 years ago____the first clock with a face and an hour hand was made.

问题描述:

It was about 600 years ago____the first clock with a face and an hour hand was made.
A.that B.until C.before D.when
很多人问过这道题了,因为它是强调句,所以用it was ...that.
但为什么不能选when呢?我理解句意是:六百年前第一台钟被制造出来.那六百年前是时间,对于时间应该可以用when的啊.

因为when 要和具体的时间“点”搭配,about 600 years ago是表示从造钟到现在“经过”了多少时间,所以不能用when.
你看下面这句:It was yesterday when he got there.
句中yesterday 表示的是具体的过去的某个时间,而不是从过去到现在经过的“一段时间”所以可以用when