问题

How long have you known the doctor —_________he helped me three years ago.
A: When
B: Before
C:Because
D: Since
B: Before
C:Because
D: Since
正确答案是:
同类题型
____, Tom. Is this your pen—No, it isn’t. I think it’s ____.
The thief drove as fast as he could toescape ________ by the police.
Are you going to have a holiday this year?—I’d love toI can’t wait to leave_____this place.[ ]
After he retired, he keeps on taking exercise to kep fit______a good diet
Last night, the shop was closed she didn’t buy any chocolate.