你好。sing to常表示“和着/伴着……唱歌”，如：sing to the music/pinao。而sing for sb.表示“为某人唱歌”。

　　你好！sing to 后面加的是歌唱的对象，表示方向性；sing for是为了谁歌唱，表示目的性。

　　for有很多种用法： 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。 to的用法: 一：表示相对，针对 be strange (common, new, familiar, peculiar, distinct, sensitive, immune, vulnerable, indispensable) to Air is indispensable to life. Aircrafts are vulnerable to interference caused by radiation. This injection will make you immune to infection. 二：表示对比，比较 1：以-ior结尾的形容词，后接介词to表示比较，如：superior ,inferior,prior,senior,junior The quarrel happened prior to my arrival. 2: 一些本身就含有比较或比拟意思的形容词，如equal，similar，equivalent，analogous A is similar to B in many ways. 3：表示一些先后顺序的形容词，如：second,subsequent,next,preliminary,preparatory Subsequent to the war,they returned to their hometown. 4: to也偶尔出现在个别动词之后,与动词形成固定词组,表示比较,如:prefer to,compare to,in contrast to compare to sth.表示比喻或比拟,而compare with sth.表示比较,如: World is usually compared to a stage Compared with his past,he has changed a lot. Prefer的正确句型是:prefer A to B或prefer doing A to doing B,但当prefer后接动词不定式时,表示比较的介 词to就要改成rather than ,如: The undaunted soldier preferred death to surrender. Many people prefer spending money to earning money. They prefer to pursue careers rather than remain home as house wives. 5: to与及个别的名词构成比较之意,如:alternative Going to an under water concert is a great alternative to going to dinner. 三: 表示修饰关系 1: 表示回复,反应意思的词,如:answer to question, solution to problem,response to inquiry,reaction to proposal,reply to letter 2: 表示建筑构件的词汇,如: entry,entrance,approach,access,passage,exit,vent,path the approach to a bridge引桥 the approach to science Half of the population was estimated to have no access to the health service. The access to education 接受教育的机会 The access to medical care 享受公费医疗的权利 3: 表示人物职位和官衔的词,如:assistant to manager, ambassador to Spain, successor to tradition, heir to throne,deputy to the National People’s Congress advisor to the Prime Minister 4: 表示权利和许可的词汇,如:right,admission The employee finally got the admission to the boardroom. Everyone has an equal right to …….. 5: 表示栅栏或障碍的词汇,如:bars to development,the ba

　　sing to sb. 对着某人唱歌。 sing for sb.为某人唱歌。真巧，今天写日记就用到这个。