(1)動詞不定式： 由 to + 動詞原形構成。 可以做主語，賓語，賓補，定語，表語和狀語

主語

1. To get there by bike will take us an hour

賓語

2. The river failed to see the car in time 

賓補

3. We believe him to be guilty

定語

4. The next train to arrive is from seoul

表語和狀語

5. My suggestion is to put off the meeting
6. I come here only to say goodbye to you
 

（2）動詞原形 + ing 可作動名詞用，具有動詞的特徵和變化形式，但在句子中的用法及功能類同名詞： 在句子中可以作主語，賓語，表語，定語。它也可以被副詞修飾或者支配賓語

1. Reading is an art
2. They went on walking and never stopped talking
3. Your task is quickly cleaning the windows
4. This is a reading room

（3）假主語 / 真主語

to 不定式或動名詞可以在主語的位置上， 但一般用 it 代替它作形式主語，這種情況 it 叫形式主語

1. It's a great honor to be invited
2. It is no use crying over spilt milk
 

在賓語的位置上，用 it 代替它作形式賓語，這種情況 it 叫形式賓語

1. We think it important to learn English
2. I found it pleasant walking in the park 

（4）對動名詞或不定式進行否定時，在不定式或動名詞前加 not 否定就可以了

1. He pretended not ro see her
2. He regrets not joining them