问题
I had not been reading for half an hour_____ I heard steps outside[ ]
A: while
B: as
C: when
D: since
B: as
C: when
D: since
正确答案是：
同类题型
I hear Sam has gone to Qingdao for a holiday.—Oh, how nice! Do you know when he________
It’s time _____ lunch.—OK. Let’s _____.
Be quiet _______ you should wake the baby
Tan Dun won an Oscar ____ his music ____ the film Crouching Tiger, Hidden Dragon.
I have ____________ homework to do and I’m _______ tired now.