before=infrontofHewasobviouslyverynervousandforsomeminutesstoodawkwardlybeforethemicrophone.before应该用在时间,infrontof才用位置为什么这里不用infrontof而用了before?

　　before=infrontof

　　Hewasobviouslyverynervousandforsomeminutesstoodawkwardlybeforethemicrophone.

　　before应该用在时间,infrontof才用位置

　　为什么这里不用infrontof而用了before?