David didn’t give up ______ he had failed in the experiment four times.
#58224
A
if
B
while
C
though
D
since
推荐题目
I enjoyed your lecture very much, ______ there were some parts I couldn’t quite understand.
#55770
A
because
B
unless
C
after
D
though
—Mum, what’s the time now?—It’s already half past seven. Be quick,_____ you will be late.
#57058
A
if
B
or
C
and
D
until
–What is your sister going to be ________ she grows up?–She is going to be an engineer.
#56613
A
before
B
although
C
when
D
unless