So far no life has been found outside the earth, but while some scientists are actively searching for living things in outer space, others firmly believe there ____ .
#88293
A
mustn’t be
B
may not be
C
can’t be
D
won’t be
推荐题目
You_____make such mistakes again.
#88888
A
should never
B
should not always
C
would always not
D
would not forever
It’s high time that we _____ home and _____ supper now.
#89215
A
go…have
B
went…had
C
go…should have
D
went…to have
— You could have asked Mr. Richard for help. He’s kind-hearted.— Yes. But that _______ him a whole day.
#87158
A
would have taken
B
had taken
C
would take
D
took
(2012·北京高考)Don't handle the vase as if it ________ made of steel.
#86522
A
is
B
were
C
has been
D
had been
It’s required that mineral resources_______ hand in hand with the local environment protection.
#87634
A
be exploited
B
exploit
C
have exploited
D
exploited