这个英语题为什么选A不选DIt was about 600 years ago ()the first clock with a _英语解答

这个英语题为什么选A不选D
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

人气：278 ℃　时间：2020-04-01 03:25:53

解答

看从句：the first clock with a face and an hour hand was made.是一个不完整的被动句.所以要用that（关系代词）来补充完整.when是关系副词,如果从句时一个完整的句子（主谓宾/主系表/……皆全）才用改it + be动...