我们知道，在英文中，不定式to do 可以作名词的后置修饰语，构成三种搭配关系：主—动关系、动—宾关系和同位关系。其实，作名词的后置修饰语，除了用to do，还可以用“介词+doing”的形式。
有些名词，其后的修饰语一般用to do。这些名词有：ability, agreement, ambition, anxiety, curiosity, disposition, mind, obligation, permission, refusal, reluctance, temptation, tendency和wish等。
They have no ability to win the game. 他们没能力赢得这场比赛。
We have signed an agreement to rent the house. 我们已签下了租房协议。
She is under no obligation to buy anything for him. 她没必要给他买东西。
Wood has a tendency to swell if it gets wet. 木材遇潮易胀。
有些名词，其后通常接“介词+-ing分词”作后置修饰语，而一般不接to do，例如：aptitude, delay, difficulty, excuse, experience, interest, genius, habit, hope, idea, method, movie, object, passion, plan, possibility, skill和success。
The little boy has a great aptitude for finding something new. 这个小男孩有发现新奇事物的才能。
Miss Yang has much experience in teaching English. 杨老师在英语教学方面经验丰富。
He has little hope of passing the exam. 他没有希望通过考试。
We must improve the method of teaching English. 我们必须改善英语教学的方法。
除了以上两种情况所介绍的名词外，还有一些名词，后面接“名词+to do”和“名词+介词+doing”两种形式皆可以，意义上也无区别。如：attempt, chance, effort, freedom, intention, necessity, opportunity, reason, time和way。
Although they had made an effort to finish the task, they failed at last.
=Although they had made an effort at finishing the task, they failed at last.
There is no necessity to buy so many things.
=There is no necessity of buying so many things. 没必要买这么多东西。
I hope that I can have the opportunity to speak to you alone.
=I hope that I can have the opportunity of speaking to you alone.