光隔离器依据（）工作。
参考答案：法拉第旋转效应
The money collected should be made good use _____ the people who suffered great losses in the earthquake.
A．of to help
B．to help
C．of helping
D．to helping
垄断竞争厂商长期均衡时，不但要求MR=LMC，而且要求（）
A.P=LAC
B.P>LAC
C.P<LAC
