They were surprised that a four-year-old boy should work out such a difficult problem ____ they themselves couldn’t.
#80212
A
once
B
then
C
while
D
if
推荐题目
After studying mass of data，they drew a conclusion________China is still a developing country.
#30622
A
that
B
which
C
／
D
where
I’ve got a lot of books, ________ are written in foreign languages.
#34527
A
and most of which
B
some of which
C
some of them
D
most of these
The police stopped the car______ speed was more than 120km per hour.
#33272
A
whose
B
which
C
of which
D
that
___ she spoke, I ___ realize she was a Japanese.
#79762
A
When, /
B
Until, didn't
C
Before, don't
D
till, didn't