Air pollution is getting more and more serious, so we must take action ________ it is too late.
#30412
A
before
B
after
C
until
D
when
推荐题目
I can judge which part of China you come from you open your mouth.
#30139
A
while
B
the moment
C
since
D
every time
—Where's that report?—I brought it to you ________ you were in Mr.Black's office yesterday.
#30686
A
if
B
when
C
because
D
before
To show our respect, we usually have to take our gloves off ______ we are to shake hands with.
#32576
A
whichever
B
whenever
C
whoever
D
wherever
_____ computers are convenient to us in daily life, it may also cause other problems.
#33235
A
Whether
B
Because
C
As
D
While
______his food______, the man had to come out of his hiding place.
#33876
A
Since; runs out
B
Because; ran out
C
With; run out
D
For; running out