省略句的常规语法要点。

Answer 1

Ⅰ、状语从句中的省略用法
一、如果从句的主语和主句的主语一致，且从句的谓语含有be动词的某种形式（am/is/are/was/were），可同时省略从句的主语和be动词的某种形式。
1、when，while引导的时间状语从句
e.g. Do be careful when (you are) crossing the street.
When/While (I was) on my way to work, I met her.
2、if，unless，once引导的条件状语从句
e.g. If (it is) properly treated, waste will do no harm to the environment.
I’ll not go to the party unless (I am) invited.
Once (you are) caught stealing in a supermarket, you will be punished.
3、though，although，whether，no matter whether/what/how/who等引导的让步状语从句
e.g. He was happy, though/although (he was) poor.
Whether (she is) sick or well, she is always cheerful.
No matter how/However hard the task (is), we must fulfill it in time.（注：从句的主语和主句的主语不一致时，只省略从句中的be动词形式）
4、as if，as though引导的方式状语从句
e.g. He rubbed his eyes and yawned as if/though (he was) waking up after a long sleep.
He stood up as if/though (he wanted) to leave.（as if/though + to do表示一个将来的动作）
二、than，as引导的比较状语从句中的省略用法：当不同的主语进行比较时，一般省略从句中的谓语；当从句中的主语与谓语（be动词除外）和主句中的主语与谓语相同时，通常省略从句中的主语和谓语，只保留比较部分。
e.g. He is taller than his brother (is).
I have as much as confidence in you as (I have confidence) in him.
三、以if从句为代表的状语从句中的特殊省略用法：通常省略了it is，that is，there is/are。
e.g. If (it is) possible/necessary, this old temple will be rebuilt.
If (that is) so, I will call you back at 5:00 pm.
There are only a few books in our school library, if (there are) any.
Ⅱ、定语从句中的省略用法
关系词的省略 关系代词that，which，whom等在限制性定语从句中充当宾语且不位于介词之后时，可以省略；in which或that在先行词way后作方式状语从句时可省略。
e.g. The man (that/who/whom) you visited last night is my grandpa.
I don’t like the way (in which/that) you treat the girl.
Ⅲ、虚拟语气中if及should的省略
1、当条件状语从句中有were，had，should等时省略if，把它们提至句首，形成倒装句。
e.g. If I were a teacher, I would be strict with my students.
= Were I a teacher, I would be strict with my students.
2、Suggest，insist，order，require等表示建议、要求、命令的动词后接的名词性从句中，谓语动词常用“should+动词原形”，should可以省略。
e.g. The doctor suggested that he (should) try to lose weight.
Ⅳ、不定式符号to的省略
1、感官动词see，hear，feel，watch等和使役动词have，make，let等后接不定式作宾语时，不定式省略to。
2、do nothing but，can’t help but等结构常接省略to的不定式。
e.g. We didn’t do anything but stay at home watching TV yesterday.
Hearing the news, she couldn’t help but cry.
3、在特定语境中为了避免重复，当不定式再次出现时，在want，wish，hope，try，plan，like，love，hate后往往只保留to，而省略后面的动词。但不定式后有be，have时，也保留be和have。
e.g. My parents encouraged me to go to college, but I didn’t want to.
Ⅴ、So和not的替代性省略
用于避免重复前面所说过的内容，替代词so/not替代肯定或否定的名词性从句。可与believe，do，expect，fear，guess，hope，say，speak，suppose，think，I’m afraid等连用
e.g. – Do you suppose he is going to attend the meeting? – I suppose not.
Ⅵ、日常交际中的省略
在情景会话中，答语常常省略不会引起歧义的主语、谓语或宾语部分，而只保留对方希望了解的内容。在复合句或并列句中，也有省略主、谓、宾的情况。
e.g. – How many copies do you want? -- (I want) Three copies, please.
-- Have you ever been to the Great Wall? -- No, (I have) never (been to the Great Wall).

Answer 2

省略句是英语的一种习惯用法。按照语法的分析，句子应该具备的成分，有时出于修辞上的需要，在句中并不出现，这种句子叫做省略句（elliptical sentences，这种语法现象称为“省略”（ellipsis or leaving words out。其特点是：虽然省去句子语法构造所需要的组成部分，但仍能表达其完整的意义。省略形式多样，从单词、短语到分句，都可以省略，而且各有一定的衔接关系，不容臆断。