Question

【題目】Scientists are convinced _______ the positive effect of laughter _______ physical and mental health.

A.in; onB.of; onC.on; atD.in; at

Answer 1

【答案】B

【解析】

考查介詞。句意：科學家們確信笑對身心健康有積極的影響。be convinced of是固定句式，意為“相信……”；effect經常和on搭配，表示“對……的影響”。故選B。