The rivers will become dirtier and dirtier ______ we take action to protect them.
#56392
A
since
B
if
C
until
D
unless
推荐题目
A tourist will easily lose his way in Beijing ______ he has a map or a guide.
#58451
A
if
B
because
C
unless
D
when
—Will you come______have a drink with me? —I’d love to, _______I’m too busy these days.
#55358
A
and, or
B
and, but
C
or, but
D
or, and
—Tom, you look tired this morning. What’s wrong?—I was so busy that I didn’t go to bed _____ 12 o’clock last night.
#58255
A
until
B
when
C
though
D
unless