No smoking! Thanks s lot!等。
(1) 口语中，一、二、三人称的主语，有时还包括谓语都可以省略。如：(It is)Nice to see you!
(This is) Li Ming speaking.
I'm going to visit Tom's (house).
I met him at the tailor's (shop).
(3) 两个或两个以上的动词不定式并列在一起时，第一个不定式带to，后面的不定式可省to.如: His job is to clean and mend the machine.
(4) 主(宾)语补足语中的to be常省略。He was considered (to be) the best student in the class.
(5) There be结构中 there be可同时省略，或只省略there.如：(Is there) Anything wrong?
(6) 表示年龄的years old, 表示钟点的o'clock, minute等常省略。如：What time is it now? It's ten (o'clock).
(1) 宾语从句，以which, when, where, how和why引起的宾语从句谓语与主句谓语如相同，可省略从句中全部谓语，甚至主语也可省略，仅保留wh-一词。如：
He will come, but we don't know when (he will come).
He didn't come, I wondered why (he didn't come).
The man (whom) I saw in the street the other day is my teacher.
I'll tell him that when (it is) possible.
I won't go there unless (I'm) invited.
例1 A beam of light will not bend(弯曲)round corners unless____ to do so with the help of a reflecting device(反射装置)。
A made B being made C having made D to be made
解析：该题正确答案为A。 unless后省略了it is. make sb (sth) do sth变成被动语态则为sth/ sb be made to do.
例2 While ____my homework, I heard a cry for help.
A do B did C doing D having done
解析：该题答案为C。该空处省略了I'm,相当于while I'm doing my home work.如：While playing guitar, he is singing.
it 与there be的用法
I have a new pen. It is beautiful.
The Browns have a new baby. It's cute.
(2)用来表示时间、天气、距离等，如，It's twelve o'clock now.
It's fine today.
It's no good telling him that.
It's necessary for you to do so.
(4)用在强调结构中，构成强调句式：It is/was +被强调部分+that/who/whom +句子其余部分，可强调除谓语以外的句子其他成分，如，
It was this morning that I saw him in the street.
It was I who saw him in the street this morning.
It was in the street that I saw him this morning.
It was him whom I saw in the street this morning.
There are a lot of students playing on the ground.
There is going to be a test this afternoon.
There is a pen and three pencils in the pencil-box.
There isn't a desk, a bench and three chairs in the room.
There are lots of people like it, aren't there?
there be句型，谓语动词除be之外，还可用其他表示存在，位置移动等意义的不及物动词或词组，如exist, stand, lie, enter, come, happen to be, appear to be等，如，
There stands a house at the foot of the hill.
there be句型表示"存在"而have表"有"、"拥有"，所以there be中 be不能换成have，但当have表示事物的特征时，可用"主语+have"结构替换there be 句型，如：
There are five doors in the house.
The house has five doors.
there be 的其它句型：
1、There must be a meeting in the office.
2、There have been great changes since 1979.
3、There being no bus, we had to walk home.
例1 ____ that he went to sleep.
A It was until midnight B That was until midnight
C It was not until midnight D That was not until midnight
解析：该题答案为C。强调until结构时，要将否定词not移到until前。又如：He didn't leave until twelve 改为It was not until twelve that he left.
例2 There are a lot of students ____ in the class room.
A talk B talking C talked D to talk
解析：该题正确答案为B。 There be句型为倒装句，可换为A lot of students are talking in the class room. 又如：There is a lot of noise heard out in the street.