Is it only when you fail _________ you will be aware of your mistakes?
#85051
A
that
B
and
C
or
D
unless
推荐题目
I must find out why____so many students made the same mistake. 
#84856
A
is it that
B
was it which
C
it is what
D
it was that
When asked to explain ________ made his lessons so exciting, the teacher kept silent.
#84693
A
what it was that
B
that what it was
C
what was it that
D
that what was it