问题

The children ____ very quiet;I wonder what they ____ up to
A:when
B:that
C:since
D:before
B:that
C:since
D:before
正确答案是:
同类题型
Oh, it’s you! I _______________ about our meeting here
The reason why he was late was ___he had taken a wrong bus.
Mary, put on your coat, ______ you’ll catch acold.
Look! The police ______ the food onto the bank of the river.
Kitty, will you go to see Spider-man 3 with us this evening— Sorry. I _______ the film already.