关于介词与连词的问题"人称代词用于as和than之后,如果as和than用作介词,往往用宾格；如果as和than用作连词

关于介词与连词的问题
"人称代词用于as和than之后,如果as和than用作介词,往往用宾格；如果as和than用作连词,则往往用主格." 1、She reads faster than __ (he/him)2、I am a good student as __ (he/him) 请问如何分辨 than as何时为介词,何时为连词?

一、as作连词的用法 　　1. as...as的用法 　　as...as意为"和……一样",表示同级的比较.使用时要注意第一个as为副词,第二个as为连词.其基本结构为：as+ adj./ adv. +as.例如： 　　(1)This film is as interesting as that one.这部电影和那部电影一样有趣. 　　(2)Your pen writes as smoothly as mine.你的钢笔书写起来和我的一样流畅. 　　其否定式为not as/so +adj./ adv. +as.例如： 　　This dictionary is not as/so useful as you think.这本字典不如你想象的那样有用. 　　若有修饰成分,如twice, three times, half, a quarter等,则须置于第一个as之前.例如： 　　Your bag is twice as expensive as mine.你的袋子比我的贵一倍. 　　几个关于as...as的常见句型： 　　(1)as...as possible 　　Please answer my question as soon as possible.请尽快回答我的问题. 　　(2)as...as usual/before 　　She looks as pretty as before.她看起来和以前一样漂亮. 　　(3)as long as... (引导条件状语从句) 　　It took us as long as three years to carry out the plan.我们花了长达三年的时间才完成这项计划. 　　(4)as far as 　　He walked as far as the railway station yesterday evening.昨天傍晚,他一直散步到火车站. 　　(5)as well as 　　She cooks as well as her mother does.她烧菜烧得跟她母亲一样好.　　2. as用作连词引导时间状语从句 　　as与when,while都是引导时间状语从句的从属连词,含义都是"当……的时候".但它们有区别：用when时,从句的动作可以与主句的动作同时发生,也可以先于主句的动作发生；用while时,从句的动作为一过程,主句动作与从句动作同时进行或在从句动作过程中发生；用as时,主句和从句的动作同时发生,具有延续的含义.例如： 　　(1)It was snowing when he arrived at the construction site.他到达工地时,天正在下雪. 　　(2)He was watching TV while his mother was cooking.他母亲做饭时他在看电视. 　　(3) You will grow wiser as you grow older.你会随着年龄的增长而越来越聪明. 　　3. as用作连词引导原因状语从句 　　as,because,since都可以表示因果关系,连接原因状语从句,含义是"因为,由于",但它们有区别：because表示的语气最强；as一般放在句首,语气较弱,较口语化；since常常用在书面语中,表示多为对方已知的、或稍加分析便可得知的原因,有时可译作"既然".例如： 　　(1) He will succeed because he is in earnest.他一定会成功,因为他很认真. 　　(2) Since you are so sure of it he”ll believe you.既然你对此如此有把握,他会相信你的. 　　(3) As rain has fallen, the air is cooler.因为下过雨,空气比较清爽. 　　4. as作连词引导让步状语从句 　　as与although (或though),however (或no matter how)等都可以引导让步状语从句,含义是"虽然,尽管",但它们有区别：although语气稍正式些,可放在句首,也可放在句中,主句中不能再用but,但可以用yet；as所表示的语气较强,引导的让步状语从句用倒装语序；however引导让步状语从句时,它的后面可跟形容词或副词,也要用倒装语序.例如： 　　(1) Although he is quite old, he still jogs every day.他虽然年纪相当大,仍然每天慢跑. 　　(2) Strange as it may seem, nobody was injured in the accident.这次意外虽然显得令人不可思议,却没有人受伤. 　　(3) However hard he may try, he will not attain his goal.无论他怎样努力也达不到目标. 二.as作介词的用法 1."作为","以……身份".例如： 　　He came to China as a tourist five years ago.他五年前以游客的身份来过中国. 2.像,如同,跟…一样： I am a good student as him. 我跟他一样都是好学生.三.than作为连词1.在表意愿的句型中,构成 would do sth rather than do sth, would rather do sth than do sth或prefer to do sth rather than do sth结构,意为“宁愿做……而不……”.例如：
The soldiers would rather die than surrender. In winter the children prefer to watch TV at home rather than go camping. 2.no sooner …than意为“一……就……”,引导时间状语从句,且当此结构置于句首时,主句要倒装.例如：
I had no sooner reached home than it began to rain. 我一回到家就下雨了. No sooner had I reached home than it began to rain. （No sooner 置于句首要倒装）四.than作介词,引导比较的第二部分 I am older than her.我比她大. 总之,作为连词时通常引导句子,人称代词作句子的主语,当然用主格.作介词,后面只能连接词或短语,人称代词用宾格.as,than的用法很多,不要单纯从词法上记忆,要掌握它的句型,短语,熟记每个用法的例句.