Scientists are convinced ___ the positive effect of laughter ___ physical and mental health.
#28425
A
of; at
B
by; in
C
of; on
D
on; at
推荐题目
You can’t take the lift because it is _______. 
#27511
A
in order
B
in order to
C
out of order
D
on order
I’m taller than Mike ___ head.
#29052
A
to a
B
by a
C
for the
D
in the