－Are you sure you have to? It’s been so late. Make it another time?－I don’t know ________ I can do it if not now.
#31948
A
how
B
what
C
when
D
that
推荐题目
It is a difficult problem for high school students they can properly use the Internet．
#30653
A
what
B
where
C
when
D
whether
You said boys were cleverer than girls. That is _______ I disagree.
#34321
A
what
B
where
C
which
D
why
________scores of times, but Derek still couldn’t understand how to use past participle in a concrete situation.
#32441
A
Having explained
B
Having been explained
C
Though it was explained
D
It was explained
In the US they focus on creative thinking skills, _____ in China they only focus on theory．
#32741
A
since
B
when
C
while
D
now that