问题 选择题

___is certain is ___prevention is more important than treatment .

A.It;that

B.What;that

C.As;what

D.What;what

答案

答案:B

B “____is certain”在句中做主语,主语从句缺少一个主语,需要用What; “___prevention is more important than treatment .”系表语从句,句意与结构完整,只有that,可以这样用。

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