- 试题详情及答案解析
- 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：C
- 试题分析：考查介词。 be convinced of sth 意为“对某事确信”； effect on sth是“对某物产生的效果”。句意：科学家确信笑会对人的身体和精神健康产生积极效果。故C正确。
考点：考查介词