英语题This was a time----there were still slaves in the U.S.A.

问题描述:

英语题This was a time----there were still slaves in the U.S.A.
A.whenB.at thatC.that D. where
这个应该选哪一个啊
麻烦详细一点啊,说下为什么~
为什么不能是C啊,同位语从句啊

用when,
时间状语从句.
this was a time明显是一个跟时间有关的行为就要发生或者已经发生,所以后面必跟表示时间的词语.