rate of 与rate for

lingxia

OG-13. State officials report that soaring rates of liability insurance have risen to force cutbacks in the operations of everything from local governments and school districts to day-care centers and recreational facilities.
(A)    rates of liability insurance have risen to force
(B)    rates of liability insurance are a force for
(C)    rates for liability insurance are forcing
(D)    rises in liability insurance rates are forcing
(E)    liability insurance rates have risen to force
In choices A and B, rates of is incorrect; when rates means "prices charged," it should be followed by for.

我怎么没明白它在说什么？
到底rate of和for有什么区别啊？
谢谢

dreadpower

查了字典，rate作价值讲，都接for，应该是固定用法，不是区别的问题