介词in,on 和at的主要用法是什么

知识要点：
1、反意疑问句.
2、介词in,on 和at的主要用法.
重点、难点：
一、由一个陈述句,后面附上一个简短问句的疑问句叫做反意疑问句,如果陈述句是肯定式,简短的问句用否定式；如果陈述句是否定式,问句用肯定式.
e.g.：He goes to school at seven,doesn’t he
He does’t go to school at seven,dose he
表示疑问句时用升调,表示强调时用降调.
e.g.：He is a teacher,isn’t he （他是教师,是不是?）
She is a doctor,isn’t she （她是医生,不是吗?）
注意以下两点：
1、简短问句的否定形式,要用缩写形式,不能出现not,主语要用人称代词不能用名词,there be句型,仍用there.
e.g.：Her mother is a doctor ,isn’t she?
There is a book on the desk,isn’t there?
2、对反意疑问句的回答,是根据事实,而不是根据问题的提法.
e.g.：He isn’t a doctor,is he (他不是医生,是吗?)
Yes,he is .(不,他是医生.)
No,he isn’t.（是的,他不是医生.）
二、表示在…年,月,季节用in.
e.g.：Jim was born in 1981.
It’s cold in January.
It often rains in summer.
表示在…天用on.
e.g.：Kate was born on January 5,1980.
He is often free on Saturday.
表示在…点钟在at.
e.g.：Let’s begin the meeting at 2:00.
下面是本单元需要掌握的词汇及语言点：
1、Last除了作形容词,意为“上一个的”还能用作动词,意为“持续”.
e.g.：去年last year?今年this year?明年next year
上周last week?本周this week?下周next week
The rain lasted for three days.这雨一连下3天.
It is very cold in winter.It lasts from February to April.
冬天很冷,从二月份持续到四月份.
2、take off脱下?put on穿上
这两个短语都是强调动作的,是一个瞬时性的动词短语.
3、Where are you from 你是哪里人（你从哪里来?）
= Where do you come from?
4、be different from 和…不同.
e.g.：I think English names are different from Chinese names.
我认为英文名字和中文名字不同.
5、What’s the weather like…?…天气怎么样?
e.g.：What’s the weather like in Beijing?北京的天气怎么样?
What’s the weather like in February?二月份的天气怎么样?
6、I hope you are well.我希望你身体健康.
well只有在表示“身体健康状况”时,才可以用作形容词,意为“健康的、结实的”除此之外,都用作副词.
e.g.：I hope your family are well.祝你的全家身体健康.
She sang well.她唱得很好.
He speaks English well.他英语说得很好.
7、be good for 有益于……,适宜于……
e.g.：It is good for sports.（这天气）适宜于体育运动.
Don’t read in the sun.It’s bad for your eyes.别在阳光下看书,这对你眼睛不好.
8、go swimming 去游泳
go skating 去滑冰
go shopping 去买东西
9、help sb.with sth.帮助某人做某事.
e.g.：We often help him with his English.我们经常帮他学习外语.
They helped the farmers with the harvest.他们帮助农夫们收割庄稼.
10、enjoy doing sth.喜欢做某事.注意enjoy后面出现的动词,要用-ing形式.
e.g.：They really enjoyed working on the farm.他们确实很喜欢在农场里劳动.
They often enjoy watching TV in the evening.他们常喜欢晚上看电视.
11、get ready for 为…做好准备 =be ready for
e.g.：Are you ready for the exam?=Do you get ready for the exam?
你已经为考试做好准备了吗?
12、I like spring best.我最喜欢春天.（这里best是副词,best前可以不用the）
比较：Spring is the best time of the year.（这里的best形容词,前面一定要用the）
13、在以下两个例句中,“get”和“turn”都是连系动词,后接形容词,构成“系表结构”
e.g.：The weather gets warmer and the days get longer.
The trees turn green.
注意：虽然“turn”与“get”都表示变成的意思,但不能互换,因为不同的连系动词连接不同的形容词作表语.