请问：They fell short of what their parents expected of them.
问题描述：
请问：They fell short of what their parents expected of them.
这里出现的两个“of”起什么作用?
fell short 翻遍词典都没有这种搭配啊？
答
他们达不到父母对他们的期待.
of后是what的从句.