1.某些動詞后要接不定式

某些及物動詞后只能接不定式作賓語，其中最常用的動詞有agree, afford, arrange, appear, ask, attempt, care, choose, continue, decide, demand, desire, determine, expect, fail, fear, forget, hate, hesitate, hope, intend, learn, like, love, manage, mean, neglect, offer, plan, prefer, prepare, pretend, promise, refuse, regret, remember, seek, tend, try, volunteer, want, wish等。

What do you plan to do tomorrow?

She hated to move from such a nice village.

In class teachers should try to get feedback from their students

2.不定式的被動式

不定式有被動式，當不定式的邏輯主語是這個不定式所表示的動作的承受者，不定式要用被動式，在句中可作主語，賓語，定語，狀語，復合賓語等。作定語時，通常表示在謂語動作后將要發生的動作。

The last question to be discussed today is how to do the job more efficiently.

She preferred to be given more difficult work to do.

3.不定式的完成式

當不定式的動作發生在謂語動詞的動作之前，不定式要用完成式，在句中可作賓語，狀語以及構成復合賓語，復合謂語。

She seemed to have heard about the news already.

He was believed to have been a very rich man.

4.不定式的完成被動式

當不定式的邏輯主語是這個不定式所表示的動作的承受者，且不定式的動作發生在謂語動詞的動作之前，不定式要用完成被動式，在句中可作主語，賓語或構成復合賓語，復合謂語。

The forest fire is reported to have been put out last night.

It is supposed to have been finished without referring to any reference books.

5.帶邏輯主語的不定式短語

不定式可以有邏輯主語，其構成形式為“for +代詞的賓格(或名詞) +不定式”。 帶邏輯主語的不定式短語可在句子中作主語、賓語、表語或狀語等。

It is not easy for you to catch up with them in a short time.

I think it better for you to see the doctor.

What we want is for you to understand the matter clearly.

I sent him some pictures for him to see what Paris is like.

6.帶疑問詞的不定式短語

不定式前可以加某些疑問代詞，如who、what、which,或疑問副詞，如when、where、how、why等，構成一種特殊的不定式短語，可在句子中作主語、賓語、表語或狀語等。

How to improve English is often discussed among the students.

We haven’t decided when to visit the place.

The most difficult thing in learning English is how to speak the language well.

You haven’t answered my question where to get these books.

7.某些動詞后的不定式作賓語補足語時，不定式不帶to，這些動詞是feel, have, hear, let, make, notice, see, watch等。

Suddenly I felt the atmosphere in the room become tense.

I often hear them sing this song.