后面可以跟to,例如:
1.It's difficult for them to get here much before seven.他们很难在7点以前早早地来到这里。
2.We had no end of trouble getting them to agree.我们费了九牛二虎之力才使他们同意。
3.We can't expect them to just roll over for us.我们不能指望他们会乖乖地向我们认输。
具体情况具体分析。有的时候可以跟to.有的时候可以跟for.,还有的时候可以跟of.