什么是不定词

不定词具有名词, 形容词, 及副词 性质,
因具有名词性质, 故在句中可当(1) 主词 (2) 补语 (3) 受词
(一) 名词:
(1) 主词: 不定词当主词, 动词采单数动词
To learn English is important.
= Learning English is important.
= It is important to learn English.
(2) 补语:
To see is to believe. = Seeing is believing.
I asked him to go with me.
I want him to wash my car.
(3) 受词:
当及物动词之受词:
S + want, need, ask , … + to+V
例: 1. I want to go to the movies with Tom.
2. I need to leave now.
3. ( 例外: Your classroom needs cleaning.)
4. He asked to go out.

(2) S +like,love, hate,
begin, start, try, + to+V
plan +Ving

I like to go swimming in summer.
= I like going swimming in summer.
形容词:
I have something to say.
I have something to do.
(三) 副词:
He got up early to catch the bus.

没固定的词,嗯.