he is looking forward to seeing you

问题描述:

he is looking forward to seeing you
为什么look要加ing

现在进行时的结构:BE +动词ING形式,而
LOOK FORWARD TO DOING STH 是固定用法:盼望做某事请问怎么确定现在进行时根据上下文,或句子中有关键的词,如now, LOOK!, Listen!等