一、what to do 和 how to do it 区别
就是字面上的区别,以 I don't know.... 为例:
I don't know what to do 是我根本不知道该做什么
I don't know how to do it 是我知道该做什么,但不知道怎么去做
二、by bus, in bus,on bus, take bus区别
1.by bus是介词结构,乘坐这种交通工具
2.in bus在车里面
3.on bus正在坐车
4.take bus是动词结构,也是指乘坐这种交通工具
三、IF虚拟语气的三种时态是什么?
1、提出将来会发生的事:主句:主语+would/should/might/could+动词原形;
从句:should+动词原形/were to+动词原形;
2、提出现在的条件: 主句:主语+would/should/might/could+动词原形;
从句:动词过去式;
例句:If he studied at this school, he would know the enviornment around the school very much.
3、提出过去的未发生的条件:主句:主语+would/should/might/could have+动词过去分词
从句:had+动词过去分词
例句: If I had read the book, I would have told you about it.
扩展资料
if的用法
if作为从属连词,可引导条件状语从句、让步状语从句和名词从句。
if引导条件状语从句,从句可为真实条件从句,也可为虚拟条件从句。如为真实条件从句,谓语用陈述语气,表示可能性很大,作“假使”“如果”解,通常用一般现在时代替一般将来时; 如果if从句中用will,表示意愿。
从句如为虚拟条件从句,谓语动词要用虚拟语气,表示可能性不大或与过去事实相反,作“要是,假如”解。可指过去的情况,也可指现在和将来的情况。指将来情况时可用were to或should。在现代口语中,一、三人称后常用was代替were。if引导的虚拟条件句中,助动词were,should,had可以移至主语前,此时if可省略。
if引导的条件从句中可以省略be和主语。
if引导的条件从句,有时后接only以加强其语气,表示说话人非常盼望某人提出的条件能够实现。
if可引导让步状语从句,作“虽然,即使”解,常和even连用。
if可引导名词性从句,作“是否”解,常放在ask, doubt, know, learn, see, wonder等动词后。一般用在口语中,而且不能用于句首。
四、as引导的状语从语都有些什么意思啊?
1.时间状语从句:
as(当……的时候), as soon as(一……就……),
As / When I came home, I met an old schoolmate of mine.我回家的时候遇到了我的一位老同学。
I’ll ring you up as soon as I get an answer from him.我一有他的答复就给你打电话。
2.原因状语从句
表示原因的状语从句可以由as(由于)
As she was ill, she didn’t come to the party.由于病了,她没来参加晚会。
3.条件状语从句
so /as long as(只要), as/ so far as(就……而言),
As/So long as we don’t lose heart, we’ll find a way to overcome the difficulty.只要我们不灰心,我们就能找到克服困难的方法。
As/So far as I know, he is an expert on DNA.据我所知,他是一个DNA专家。
4.方式状语从句
方式状语从句常由as(与……一样), as if(仿佛), as though(仿佛)等词引导:
Do in Rome as the Romans do.入乡随俗。
Leave things as they are.让一切顺其自然。
She stood at the door as if (=as though) she were waiting for someone.她站在门口,仿佛在等人似的。(由as if或 as though引导的从句中可用虚拟语气)
5.比较状语从句
as(与……一样)
Our country is as big as the whole of Europe.我们的国家同整个欧洲一样大。
The result was not as/so good as I had expected.结果不如我预料的那么好。
6.让步状语从句
连词as也可以引导让步状语从句,但从句中要用特殊语序。如:
Young as he is, he knows a lot=Though he is young 或Young though he is, he….
他虽然年轻,但懂得很多。(though 也有这种用法,可以替换as,但although没有这种用法)
though还可以用作副词,放在句末。如:
It was hard work; I enjoyed it, though.=It was hard work, but I enjoyed it.那工作很苦,但是我喜欢干。


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