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
Her grandparents are still in good health_____they are over eighty.
#57739
A
though
B
as soon as
C
until
D
because
The Nanjing Yangtze River Bridge is still very strong, ___________ it is almost 43 years old.
#58225
A
although
B
but
C
so
D
because
