优题课 - 聚名师,上好课(www.youtike.com)
  首页 / 试题 / 高中英语 / 试题详细
  • 科目:英语
  • 题型:单选题
  • 难度:中等
  • 人气:1011
题文

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

A.of; at
B.by; in
C.of; on
D.on; at
登录免费查看答案和解析

Scientistsareconvincedtheposit