有这么一道题：

I have many friends to ________ when I have trouble.

A. talk to       B. talk             C. talk about

我认为选A，可是答案是C。请您帮助分析一下，谢谢。

从语法上角度，A/C都正确，因此需要从语义上进行筛选了.

(1) I have many friends to talk to when I have trouble.

参考译文：当我有困难的时候，我有很多朋友可以进行倾诉。

=When I have trouble, I can/ will talk to many friends.

参考译文：当我有困难的时候，我可以/会向很多朋友倾诉。

(2) I have many friends to talk about when I have trouble.

参考译文：当我有困难的时候，我有很多朋友可以进行谈论/讨论。

=When I have trouble, I can/will talk about many friends.

参考译文：当我有困难的时候，我可以/会谈论/讨论/谈及很多朋友。

（备注：以上不定式的逻辑主语为句子主语，不定式与被修饰词存在逻辑上动宾关系.）

解答如下：

以上为不定式作后置定语用法

(1)talk to 侧重于一个人对另外一个人讲话.A talk to B,即A对B说话，强加直接和某人说话。

She was talking to a friend.

她正在跟一个朋友讲话。

I've asked you not to talk to that rough boy!

我说过让你别和那粗野的小子说话!

A good newspaper,I suppose, is a nation talking to itself.

我认为反映民族心声的报纸才是好报纸。

Don't talk to me about that fellow.
别跟我谈起那个家伙。

It's often helpful during an illness to talk to other sufferers.
病中与同病者谈天常是有益的。

He disdained that man for snobbishness and was unwilling to talk to him.
他鄙视那个势利小人，不愿和他说话。

They taught the little boy not to talk to strangers.
他们教育小男孩不要和陌生人说话。

She detests having to talk to people at parties.
她讨厌在宴会上为应酬而和人交谈。

He was too shy to talk to anyone at the party.
在晚会上他很腼腆，没有和任何人讲话。

Don't talk to me like that!
别那样和我说话！

(2)talk about 谈起/谈到某人/某事.强调间接谈论/谈及/讨论某人/某事。

I have some very important business to talk about.

我有重要的生意想谈。

What are you talking about?

你们在讨论什么?

Let's talk seriously about your future.

咱们认认真真地谈谈你的将来吧。

I talked yesterday about the problems facing young people in today's society.

昨天我讲了当今社会青年人所面临的问题。

We talked about what to do.

我们讨论该怎么办。

I never talk about gossip.

我从不传播流言蜚语。

Please don't talk about it in front of the children.
请不要当著孩子们谈论那事。

Don't sentimentalize when you talk about animals.
谈论动物不必忧形於色。

Steve and Jack gave a talk about their trek across the Polar ice cap. It was very interesting but it made my hair stand on end just to hear about the dangers they faced.
史蒂夫和杰克讲述了他们在极地冰盖的一段艰苦跋涉，故事津津有味，只是听到他们遇到种种险情时，我吓得很。

We can talk about this matter in private.
我们只能私下谈论这个话题。