All possible means ____ to prevent the air pollution, but the sky is still not clear.
#100326
A
is used
B
has been used
C
are use
D
have been used
推荐题目
— Why, David, you look so tired!— Well, I ________an article and I must finish it tomorrow.
#102961
A
was writing
B
will be writing
C
have been writing
D
have written
（安徽安庆2009教学质量监测） It is estimated by some experts that by the end of next year we a fall in house prices by 25%.
#104905
A
will see
B
see
C
has seen
D
will have seen
She _______ to go traveling this summer, but some extra work took up all her time.
#103183
A
had been planned
B
has planned
C
was planned
D
had planned
When you are at home，give a call to let me know you safely．
#100432
A
are arriving
B
have arrived
C
had arrived
D
will arrive