1、在以as, than, when, if, unless等引导的从句中的省略: 在有些状语从句中,如果谓语包含有动词be,主语又和主句的主语一致a),或者主语是it b),就常常可以把从句中的主语和谓语的一部分(特别是动词be)省略掉.
1）Look out for cars when crossing the street.
When taken according to the directions, the drug has no side effects.
If not well managed, irrigation can be harmful.
Though reduced in numbers, they gained in fighting capacity.
He said that no acrobat could ever perform those daring feats unless trained very young.
Once having made a promise, you should keep it.
2）If necessary I’ll have the letter duplicated.
As scheduled, they met on January 20 at the Chinese Embassy.
2、在以than a) 或 as b) 引起的从句中,常会有一些成分省略.
1）He told me not to use more material than (it is) necessary.
We should think more of the collective than of ourselves.
2）They worked with as much enthusiasm as young people (did).
He is now a vice-manager, but still often works in the kitchen as before.
Their training is free, as is all education.
We will, as always, stand on your side.
1）His life is as fully committed to books as anyone I know.
2）While standing there in her nightgown, two bullets struck the wall beside her.
·He was said to be jealous of her success.
·It was said that he was jealous of her success.
·It is supposed that the ship has been sunk.
·The ship is supposed to have been sunk.
2、担当be supposed to 与不定式的一般形式搭配时往往表示不同的意义。
·Why are you driving so fast in this area?
·You are supposed to know the speed to know the speed limit. (你应该晓得速度限制)3、双宾语及宾补结构的被动语态
·He was asked a number of questions at the press conference.
·Two days were allowed them for making the necessary preparations.
·She was called Big Sister by everybody.
1）Vi. + adv.：The plane took off two hours late.
2）Vi. + prep.：They looked round the Cathedral.
3）Vi. + prep. (有被动语态)：She’s looking after her sister’s children.
4）Vi. + adv. + prep.：I began to look forward to their visits.
5）Vt. + O(无被动语态) + adv.：Some women choose to stay at home and bring up their children.
·The children were brought up by their mother.
6） Vt. + adv. + O (无被动语态)：I am trying to give up smoking.
7）Vt. + O(无被动语态) + prep.：We talked Donald into agreement.