getting them to agree would be difficult

题目

getting them to agree would be difficult
这个句子是动词ing形式作主语吧
但是如果加it作为形式主语的话时否就要变成
it would be difficult to get them agree.

答案

句式没有错,但是少了个to,get sb to do sth是固定句式,所有正确的应该是 it would be difficult to get them to agree.