问题 选择题

Scientists are convinced ___ the positive effect of laughter ___ physical and mental health.

A.of; at

B.by; in

C.of; on

D.on; at

答案

答案:C

convince 意为“使确信,说服”,与介词of连用,意为“使(人)承认或信服”。effect 意为“作用,功效,影响”,与介词on连用,表示“对……有影响”。

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