You should not go rafting ________ you know how to swim.
#31441
A
if
B
if not
C
when
D
unless
推荐题目
Our new school was built in a beautiful place, around _____ high mountains.
#34520
A
which was
B
it was
C
which were
D
them were
—Why didn’t you apologize to her? —She drove away ______ I could say a word.
#33702
A
before
B
after
C
until
D
unless
There was a time_____we went to the country and stayed with the farmers there.
#34672
A
which
B
that
C
when
D
while
The agent was about to sign his name to the document ________，to our surprise，a stranger broke in to prevent him.
#30223
A
while
B
when
C
as
D
until