Unit 3what were you doing when the ufo arrived?【重难点分析】一. 过去进行时过去进行时表示过去某一时刻或者某段时间正在进行或发生的动作，常和表过去的时间状语连用。
过去进行时的构成：肯定形式：主语+was/were+V-ing否定形式：主语+was not (wasn't)/were not (weren't)+V-ing疑问形式：Was/Were+主语+V-ing。
基本用法：1.过去进行时表示过去某一段时间或某一时刻正在进行的动作。
常与之连用的时间状语有：at that time/moment, (at) this time yesterday (last night/Sunday/week…), at+点钟+yesterday (last night / Sunday…)，when sb. did sth等时间状语从句。
如：What were you doing at 7p.m. yesterday? 昨天晚上七点你在干什么？I first met Mary three years ago. She was working at a radio shop at the time.我第一次遇到玛丽是在三年前，当时她在一家无线电商店工作。
I was cooking when she knocked at the door. 她敲门时我正在做饭。
2. when后通常用表示暂短性动词，while后通常用表示持续性动词，因此它所引导的状语从句中，谓语动词常用进行时态，如：When the car exploded I was walking past it.= While I was walking past the car it exploded.3.when用作并列连词时，主句常用进行时态，从句则用一般过去时，表示主句动作发生的过程中，另一个意想不到的动作发生了。
如：I was walking in the street when someone called me. 我正在街上走时突然有人喊我。
4. when作并列连词，表示“（这时）突然”之意时，第一个并列分句用过去进行时，when引导的并列分句用一般过去时。
如：I was taking a walk when I met him. 我正在散步，突然遇见了他。
We were playing outside when it began to rain. 我们正在外边玩，这时下起雨来了。
特点：while之后的从句一般用：进行时态（be+doing）When之后的从句一般用：过去时态【注：本特点不是while和when的全部用法，更多的用法会在以后的学习中见到】二. 情态动词(Modal Verbs )Ⅱ情态动词：must 用于表示“必须”、“务必”注：以must引导的一般疑问句，否定回答习惯上用No，you needn’t或don't have to③. Must I pay now? Yes,you must . No, you needn’t./No,you don’t have to.三. 重点词汇1．cut v．切；剪；割cut (one’s)hair理发Be careful．Don't cut yourself．小心，别切到自己。
2．alien n．外星人An alien got out of the UFO. 一个外星人从不明飞行物里出来。
3．land v．登岸；登陆；降落 n.陆地The plane will land in ten minutes．飞机将在十分钟后降落。
A UFO landed in the middle of the field.. 一个不明飞行物降落在田野中间。
4．while conj．当……的时候；在……之时While I danced, she sang．我跳舞，她唱歌。
While he was singing, I was playing baseball. 他当时在唱歌，而我在打棒球。
5．right adv．正好；恰好The accident happened right over there．事故正好发生在那里。
He lives right in the center of the city. 他恰好住在市中心。
6．surprised adj．惊奇的；吃惊的I was surprised that he was late for the party．我很惊讶他聚会居然迟到了。
She was surprised that I didn’t know about that.她很吃惊我竟不知那件事。
注：ed形容词用于修饰Sb,而ing形容词用于修饰sth7．kid v．欺骗；哄骗I'm not kidding you．我没有骗你。
You’re kidding = No kidding.别开玩笑了。
8．anywhere adv．到处；无论哪里（用于否定句和一般疑问句中）Did you go anywhere yesterday? 你昨天去没去过什么地方?They didn’t go anywhere the day before yesterday. 他们前日天哪里也没去9．happen v．发生A funny thing happened in the subway yesterday．昨天地铁里发生了一件有趣的事。
What happened to him on that day? 那天他怎么了？（发生了什么事？）注：happen 常用于以下两个结构：sth. happen to +名词：发生于……身上happen to do sth 碰巧做某事如：She hoped nothing bad would happen to him．她希望不会有坏事发生在他身上。
10．get out of 从……出去She tried to get out of helping her mother．她尽量逃避帮助她的妈妈。
Tom got out of the lift and walked to the station. 汤姆走出电梯然后往车站走去。
11．run away 跑开；迅速离开；逃走The thief ran away when someone noticed him．当有人注意到他的时候，那个贼立刻逃走了。
12．at the doctor's 在诊所；在医院I'm thinking of going to the tailor's．在表示诊所、店铺或某人的家时，经常用名词所有格的形式。
Mr. Cool’s = Mr. Cool’s clothes store at Jason’s = at Jason’s storeShe is staying at Mary's．她住在玛莉家。
I w ant to go to the tailor’s.我想到裁缝店去一趟。
13. see sb. do sth. 看见某人做(过)某事她看见外星人出来.14. 用来表示人的强烈感情。
一般说来，感叹句是由what或how引导，句末用感叹号.感叹句结构为：What a/an + adj(形容词）+ n（名词）+（主+谓）What +adj(形容词) +名词复数+ （主+谓）What +adj(形容词) +不可数名词+ （主+谓）How +adj/adv+ （主+谓）四．词语辨析1、in front of 与in(at) the front ofin the front of 在……的前面（表示“有距离的前面”，在一个参照物的前面）e.g.: There is a car in front of the house. 房子前日面有一辆车in(at) the front of 在……的前头，前排（列）（在一个范围内的前面部位）eg. She sat in the front of the bus. 她坐在公交车的前排2、get out of 与get into 是反义词get into走进，进入eg. He get out of the car and get into the building.3、be amazing与be amazedbe amazing 令人惊奇的（修饰事物的，指某事令人惊奇，比surprising更具意外性e.g.:She has an amazing talent for music.她在音乐方面有惊人的才华。
Isn’t that amazing .那不很令人意外吗？be amazed (at sth./to do …/that 从句)（某人）对…(因…而)大感惊讶(指人作主语)eg. We were amazed at the news.=We were amazed to hear the news.我们对这个消息感到非常惊讶.4、be surprising与 be surprisedbe surprising令人惊奇的（用法与be amazing一样，也是修饰事物的）e.g.:a surprising ending 一个令人惊奇的结局be surprised (at sth./to do…/that从句) （某人）对…(因…而)感到惊奇，用法与be surprised一样，也是人作主语。
eg. They were surprising that he was badly hurt in the audient. 他们很吃惊他在那次事故中伤得很重。
5、in a tree与 on a treeeg. Are there any birds in the tree? 树上有些鸟吗？on a tree 在树上（指长在树上的东西）Look! There are many apples on the tree.6、my flight to New York 与 fly to New York前者是一个名词短语，后者是一个动词短语。
eg. Her flight to Paris is taking off at 2 p.m.She is flying to Paris at 2 p.m.五.课文解释：1. You can imagine how strange it was!你可以想象这事有多惊奇！eg. You can imagine how fast he runs!2. I followed it to see where it was goingfollow sb. to do sth. 跟随…去做…eg. Mr White followed his wife to see what was happening there.3. She didn’t think about looking outside the station.Think about (doing) sth. 她未想到去车站外看看.4. say to sb. 对某人say to oneself 自言自语e.g.: He said to himself, “Don’t be afraid.” 他自言自语,“不要害怕”5. look for 寻找（强调找的“过程”）find 找到（强调找的“结果”）eg. He l ooked for his lost key everywhere but couldn’t find it.6. It was difficult to get out of bed. 从床爬起来很难。