He tried every means to keep that kind of evens _happening again.
A. from
B. on
C. in
D. at
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_there is life on the moon is an interesting question.
A. whether
B. if
C. that
D. it
_depends on whether we have enough money.
A. everything
B. nothing
C. all
D. that
She always thinks of how she can work well.
A. 对
B. 错
Some people dump their rubbish into the river.
A. 对
B. 错