after的搭配after 后是加doing sth还是根据事态而定的do/did(动词过去式）,还是其他什么?请说具体

1.after兼有两种词性：介词和连词.
2.after做介词时,后面只能加名词/代词/动名词短语(doing sth),形成介宾短语,做句子的状语(时间状语/地点状语).
如：After finishing my homework,I watched TV last night.时间状语
She is running after me.地点状语
3.after做连词时,引导一个时间状语从句,意思是“在...之后”.该从句是个完整的句子.
如：I watched TV after I finished my homework.

因为after是一个介词，所以它后面接的是一个名词或是doing