动词不定式的句法作用
动词不定式具有名词、形容词和副词的特征，同时也有动词的特征。它在句中可以作：
1. 主语。有时用 it 作形式主语放在句首，把不定式短语放在后面。如：
To learn English well is very important.
It's very important to learn English well. 学好英语是非常重要的。
— How long does it take you to get to the airport? 你去机场用了多长时间？ — It takes me 30 minutes to get to the airport. 我去机场用了三十分钟。
2. 宾语。
Do you want to have a cup of coffee? 你想喝杯咖啡吗？
在介词 but , except 之后常用不定式作宾语。介词前如果有 to do 的某种形式时，其后的不定式一般不带 to 。如：
Last Sunday she did nothing else but do something sewing. 上个星期天她除了做了点针线活外，别的什么也没有做。
在 can not but , cannot choose but , can not help but 这类短语动词后的不定式通常也不带 to 。如：
I cannot help but tell the truth. 我不得不说实话。
3. 宾语补足语。
She asks me to come home as soon as possible.她让我尽可能快点回家。
4. 表语。
The biggest problem is how to make full use of our time and money.最大的问题是如何充分利用时间和金钱。
5. 状语。不定式可以作目的、原因、结果、方式状语等。
They worked very hard, only to get little money. (结果状语) 他们工作非常努力，但是仅仅得到很少的钱。
He stood up as if to say something.（方式状语）他站着好像有话要说。
only + 不定式表达未能预料到的结果状语。如：
He hurried home, only to find his house broken into. 他匆匆回家, 却发现房子被人破门而入了。
6. 定语。
Xiao Lin is always the first to come to the office.笑林总是第一个来到办公室。 注意作定语的不定式是不及物动词时，后面要相应的介词。
Finally they found a comfortable room to live in.最后他们找到了一个舒适的房间来住。
7. 独立成分。to tell the truth 说实话，to be frank 坦率地说，to be sure 可以肯定地说。 To tell you the truth (= To tell the truth, Truth to tell you), I don't agree with you.说实话，我不赞成你。
To be sure, some of them will say no.肯定地说，他们中有些人会反对。
动词不定式的句法作用
动词不定式具有名词、形容词和副词的特征，同时也有动词的特征。它在句中可以作：
1. 主语。有时用 it 作形式主语放在句首，把不定式短语放在后面。如：
To learn English well is very important.
It's very important to learn English well. 学好英语是非常重要的。
— How long does it take you to get to the airport? 你去机场用了多长时间？ — It takes me 30 minutes to get to the airport. 我去机场用了三十分钟。
2. 宾语。
Do you want to have a cup of coffee? 你想喝杯咖啡吗？
在介词 but , except 之后常用不定式作宾语。介词前如果有 to do 的某种形式时，其后的不定式一般不带 to 。如：
Last Sunday she did nothing else but do something sewing. 上个星期天她除了做了点针线活外，别的什么也没有做。
在 can not but , cannot choose but , can not help but 这类短语动词后的不定式通常也不带 to 。如：
I cannot help but tell the truth. 我不得不说实话。
3. 宾语补足语。
She asks me to come home as soon as possible.她让我尽可能快点回家。
4. 表语。
The biggest problem is how to make full use of our time and money.最大的问题是如何充分利用时间和金钱。
5. 状语。不定式可以作目的、原因、结果、方式状语等。
They worked very hard, only to get little money. (结果状语) 他们工作非常努力，但是仅仅得到很少的钱。
He stood up as if to say something.（方式状语）他站着好像有话要说。
only + 不定式表达未能预料到的结果状语。如：
He hurried home, only to find his house broken into. 他匆匆回家, 却发现房子被人破门而入了。
6. 定语。
Xiao Lin is always the first to come to the office.笑林总是第一个来到办公室。 注意作定语的不定式是不及物动词时，后面要相应的介词。
Finally they found a comfortable room to live in.最后他们找到了一个舒适的房间来住。
7. 独立成分。to tell the truth 说实话，to be frank 坦率地说，to be sure 可以肯定地说。 To tell you the truth (= To tell the truth, Truth to tell you), I don't agree with you.说实话，我不赞成你。
To be sure, some of them will say no.肯定地说，他们中有些人会反对。