It's uncertain ______ the experiment is worth doing.
A. if
B. that
C. whether
D. how
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______ the Games will be held in Beijing is not known. (92)
A. Whenever
B. If
C. Whether
D. That
Can you make sure______the gold ring?
A. where Alice had put
B. where had Alice put
C. where Alice has put
D. where has Alice put
____ you have done might do harm to other people.
A. What
B. That
C. Which
D. This
They have no idea at all_______.
A. where he has gone
B. where did he go
C. which place he has gone
D. where he had gone
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