We need Li Jiayuan to help with Math.
不定式作定语
不定式作定语，一般都是作后置定语，修饰前面的名词或代词。
一、不定式与所修饰词之间的关系
1. 主谓关系
被修饰的名词或代词实际上是不定式的逻辑主语。如：
We need Li Jiayuan to help with Math.
Li Jiayuan will help with Math
我们需要李嘉媛来帮助学习数学。
2. 动宾关系
被修饰的名词或代词是动词不定式的逻辑宾语。如：
I have many letters to write.
to write many letters
我有许多信要写。
3. 同位关系
不定式与所修饰的名词指的是一回事。如：
We have made a plan to learn from Lei Feng.
我们制定了一个向雷锋学习的计划。
4. 状语关系
被修饰的名词实际上表示动词不定式动作的方式、时间等。这些名词多是抽象名词。如：
That's the way to do it.
那样做才对。
I have no time to go there.
我没有时间去那儿。
二、不定式与其所修饰的词构成逻辑上的动宾关系，而该不定式为不及物动词时，其后须加上适当的介词，构成及物动词短语。如：
I am looking for a room to live in.
我正在找一间屋子住。
I need a piece of paper to write on.
我需要一张写字用的纸。
There is nothing to worry about.
没什么可担心的。
不定式作定语且所修饰的名词是
time，place或way时，不定式后的介词一般要省去。如：
He had no money and no place to live.
他没有钱也没有地方住。
三、当不定式修饰的名词或代词为不定式动作的承受者时，
不定式主动形式与被动形式的含义有所不同。试对比：
There is nothing to do.
无事可做。
(有"无聊感")
There is nothing to be done.
不能做什么了。
(即"束手无策"了)
There is nothing to see.
没有东西值得看。
There is nothing to be seen.
什么东西也看不见。
一、不定式作定语
1．作定语的不定式如果是不及物动词，或者不定式所修饰的名词或代词是不定式动作的地点、工具等，不定式后面须有相应的介词。如：
The Browns have a comfortable house to live in.
There is nothing to worry about.
Please give me a knife to cut with.
Here is some paper for you to write on.
但是，不定式所修饰的名词如果是time, place 或way时，不定式后面的介词习惯上省去。如：
He had no money and no place to live (in).
We found a way to solve this problem (in).
2．当作定语的不定式所修饰的名词或代词是不定式动作的承受者时，不定式既可以用主动
语态，也可用被动语态，但其含义有所不同。试比较：
Have you anything to send ?
你有什么东西要寄吗？
（不定式to send 的动作执行者是“你”）
Have you anything to be sent ?
你有什么要（我或别人）寄的东西吗？
（不定式to be sent 的动作执行者是“我”或“别人”）
3．用不定式作定语的几种情况：
不定式表将来：
I borrowed some books to read during my holiday. 用来修饰被序数词、最高级或
no, all, any 等限定的中心词。如：
He was the best man to do the job.
He was always the first to come and the last to leave.
She was the first woman to win the gold medal in the Olympic Games.
Women and children were the first to get into the lifeboats.
用来修饰的词是抽象名词时，常见的有：ability, chance, idea, fact, excuse,
promise,answer, reply, attempt, belief, way, reason, moment, time
等。如：
Do you have the ability to read and write English ?
I have a chance to go sight–seeing.
动词不定式作定语与被修饰的词之间有一定的逻辑关系。这些关系常见的有三种。
1、不定式与被修饰的名词或代词有逻辑上的动宾关系
He told me he had a composition to write.
I want to get something to drink.
由上述例句得知，此时的不定式必须是及物动词。
如果是不及物动词，其后就带一个结构或
含义上所需要的介词。如：
Will you please bring me a chair to sit on?
She has nothing to worry about.
2、不定式与被修饰的名词或不定代词有逻辑上的主谓关系。如：
He was the last one to arrive.
Is there anyone to take care of the children.
例句中的不定式动作的逻辑主语分别是
one和anyone。此时的不定式在意义上相当于一个
定语从句。如：
Among the men to take part in the work(==Among the men who are to take part in the work),he is probably the most active.
3、不定式所修饰的词在意义上通常是用于不定式所做某种事情的。如：
We have got a new way to kill field mice.
I think he will have a chance to go to his hometown.
可以看出，way是用来to kill field mice, chance是用来to go to his hometown。因此，这种类型的不定式译法较灵活。可译作“„的”或“来/去„”等。
