问题

roblem is said _______ three times, but he stillcan’t understand it.

A:unless
B:although
C:because
D:to have been explained

正确答案是：

同类题型

House prices vary from place to place and are usuallyhighthere are famous schools.

___ he said was quite surprising.

How was your vacation—It was great. We the mountains.

The boss looked very worried and demandedthat the work________before we went home.

We will use ______ and get ______ on the Internet.