She is writing a letter to a friend of hers,______ him to attend the party.

问题描述:

She is writing a letter to a friend of hers,______ him to attend the party.
A.to invite B.inviting
填哪一个啊,______ 处作什么语?to do可以用作补足语,而doing不可以
谁能解释一下怎么辨别补足语啊,举个例子也可以.

应该选A啦
主句是she is writing a letter
to a friend of hers是宾语补足语
to invite him to attend the party是目的状语
表示她写信的目的