to do是
动词不定式,其用法主要是从句子意思上去判断,其次是看句子结构:
一、动词不定式可以作三大状语:
1 原因状语
主系表(心理)+to do
I am glad to see you.
2 目的状语 to do sth. ,in order to do sth. ,so as to do sth.
To get up early,he goes to bed early.
3 结果状语
too...to do sth.
...enough to do sth.
so/such...as to do sth.
only to do sth.
He arrived home only to find no one was at home.
二、动词不定式作定语放在被修饰的名词之后
1 He is the first person to get home.被修饰词person与动词不定式在意思上有主谓关系。
2 He has no time to do his homework.(同位关系)
3 He has many things to do.(动宾关系)