Never______ such a difficult problem. It took me almost half an hour to work it out.
#80170
A
had I come across
B
I had come across
C
did I come across
D
I did come across
推荐题目
It was about ten minutes after we arrived at a small village __________ it began to pour down．
#79642
A
when
B
where
C
that
D
how
(2013·安徽省名校联盟模拟)West of the city , which provides a lot of job opportunities for the local people.
#79951
A
a factory lies
B
does a factory lie
C
is lying a factory
D
lies a factory
Not until ____________ to the top of the palace __________ caught.
#82669
A
he got; was he
B
did he get; he was
C
he got; he was
D
did he got; was he
Only when class began ______that he had left his book at home．
#83512
A
will he realize
B
he did realize
C
did he realize
D
had he realized