问题

Scientists are convinced _the positive effect of laughter _physical and mental health

A:of ;at
B:by; in
C:of ; on
D:on ;at

正确答案是：

同类题型

They keys were __________ to our neighboursduring our absence

How ____ can I ____ the books—Three weeks.

下列各句中加点字没有古今异义的一项是

Liz’s painful story________us with a clear example of the dangers of drug abuse.[ ]

Who is _________ inyour school, Mr Wang or Ms Lee?