问题

you clean the blackboard today, _________—– But I cleaned it yesterday
A:if
B:once
C:when
D:though
B:once
C:when
D:though
正确答案是:
同类题型
There will be _______ pollution and ________ buildings in 20 years .
Her life ________ a lot during the lastthree years.
It’s very nice ________ pictures for me.
He was about to tell me the secret________someone patted him on the shoulder.[ ]
________, I have never seen anyone who is as capable as David.[ ]