题目内容
Scientists are convinced _____the positive effect of laughter _____physical and mental health.
| A.of ;on | B.by; in | C.of ; at | D.on ;at |
A
考查固定短语。be convinced of确信; effect与介词on连用。句意:科学家相信笑对于身体和精神的积极影响。
练习册系列答案
相关题目