问题
选择题
Scientists are convinced the positive effect of laughter physical and mental health. [ ]
A. of;at
B. by;in
C. of;on
D. on;at
答案
答案：C
搜题请搜索小程序“爱下问搜题”
Scientists are convinced the positive effect of laughter physical and mental health. [ ]
A. of;at
B. by;in
C. of;on
D. on;at
答案：C