题目内容

The book was written in 1946,_____ the education system has witnessed great changes.

A. when
B. during which
C. since when
D. since then

查看答案

搜索结果不匹配？点我反馈

更多问题

The number of stars that we know _____ is now estimated at about 300 million million million.

A. to exist
B. existed
C. exist
D. exists

I hadn't been reading for half an hour _____ I heard steps outside.

A. once
B. as soon as
C. while
D. when

_____ you seem to know them, why don't you introduce me to them?

A. Since
Because
C. When
D. For

We'll let you use the room _____ you keep it clean and tidy.

A. when
B. where
C. while
D. on condition that