The alien___the UFO when I saw him.

问题描述:

The alien___the UFO when I saw him.
A.was getting out B.was getting out of C.is getting out D.is getting out of
请说出解题思路

B为什么?get ou of the UFO走出飞碟时态是过去进行时,在这个时间状语从句中,很常见为什么不加of不行呢?come out of get out oflook out of这些词组,一旦少了of,意思就变了