1.动词不定式的一般式：表示与主动词处于同一时间层面或动作发生于主动词之后。

He seems to understand what I said.

他似乎明白我说的话。

2．动词不定式的进行式：表示与主动词同时发生且动作正在进行。

The two cheats pretended to be working hard.

那两个骗子假装在努力工作。

3．动词不定式的完成式：表示不定式动作发生于主动词之前。

She seems to have seen this film.

她似乎已看过这部影片。

4．动词不定式的被动语态：表示与逻辑主语之间的被动关系。

She asked to be treated equally.

她要求被公平对待。

二、动词不定式的句法功能

不定式的句法功能是作主语、宾语、表语、宾语补足语、主语补足语、定语、原因状语、目的状语、结果状语和评论性状语。

To live in China is Mr Smith's dream.(主语)

生活在中国是史密斯先生的梦想。

She promised to give him a chance.(宾语)

她答应给他一个机会。

Your job is to wash dishes.(表语)

你的工作是刷盘子。

The teacher told his students to pay attention to their pronunciation.(宾语补足语)

老师告诉学生们要注意发音。

I was asked to help him with his lessons.(主语补足语)

我被请求帮他学功课。

Have you got a pencil to draw pictures with？(定语)

你有绘图的铅笔吗？

I'm ashamed to have to trouble you.(原因状语)

我很惭愧不得不麻烦你。

Some scientists went to Germany to attend a medical conference.(目的状语)

一些科学家去德国参加医学大会。

He was too excited to say anything.(结果状语)

他兴奋得说不出话来。

I have never seen such a person，to tell you the truth.(评论性状语)

实话告诉你，我从来没见过这样一个人。