仁爱版英语八年级下册全册语法复习.ppt课件

1、时间状语从句When/while/before/after/until/as soon as+一个完整的句子构成“时间状语从句”注意几点：一、 when/while 的区别1.when表示主从句两个动作同时发生或先后发生。而while表示主从句两个动作同时发生或强调主句的动作在从句动作进行期间发生。(1)_ they are waiting for the New Year, they listen to music , sing songs and dance.(2)_ the boy saw his mother, he stopped crying.WhileWhen2. when+短暂

2、性动词或延续性动词 while+延续性动词(1)He was doing his homework _ I saw him.(2)_she was singing, we all lost ourselves in her beautiful voice.(3)She was cooking _ someone knocked at the door.3.进行时+while+进行时She was dancing _ I was singingwhenWhen/whilewhenwhile二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while和as从句的谓语动作必须是和主句

3、谓语动作同时发生。 1从句动作在主句动作前发生，只用 when。 When he had finished his homework，he went to bed at once（finished先发生） When I arrived at the airport，the guests had left (客人)（arrived at 后发生）2. when从句动词为瞬间动词时，不能由while替换。如： When he came yesterday, we were playing basketball.昨天他来时，我们正在打篮球。 三、as引导的时间状语从句表示“当时”“一边一边”，指主句

4、的动作和从句的动作同时发生，既可以表示一段时间也可以表示一点时间。 As the time went on，the weather got worse随着时间的推移，天气变得越来越糟糕 He jumps as he goes along. 他边走边跳。The little girls sang as they went小姑娘们一边走，一边唱。 四、before引导的时间状语从句表示表示的动作发生在主句动作之后。My father booked the room before we arrives.He worked in Hangzhou before he came here.after引导

5、的时间状语从句所表示的动作发生在主句动作之后After they parked their bikes, they went to Tianan men square.I will call you after I finish the work.五、 until “直到” notuntil直到才如果主句中的谓语动词是瞬时动词时，必须用否定形式；如果主句中的谓语动词是延续性动词时，用肯定或否定形式都可以，但表达的意思不同。He waited until it was 12 oclock.He didnt go home until it was 12 oclock.I worked until

6、 he came back.我工作到他回来为止。 I didnt work until he came back.他回来我这才开始工作。六、as soon as as soon as.可译为一就，用来表示主从句的动作是紧接着发生的。eg. He will come and see you as soon as he can. 他一有空就来看你。 He rushed home as soon as he got the good news.他一得到这个好消息就奔回家。If 引导的条件状语从句Revision_selfcheck位置：从句可放在主句之前或之后，但是放在主句之前须有逗号隔开eg:如果

7、我有足够的钱，我就去环游世界If 引导条件状语从句 定义：if “如果, 假如” 它引导的句子表示某事发生所需的条件，即“在条件下，某事才能发生”，在句子中充当状语，因此称之为条件状语从句。（ If引导的条件状语从句表示假如有从句的动作发生，就会有主句动作的发生 ）If I have enough money, I will travel around the world =I will travel around the world if I have enough moneyIf条件句：条件句用于陈述语气，表示假设的情况可能发生，其中 if 是“如果”的意思。 主句一般将来时 ，从句用一般

8、现在时。 构成条件从句主句时态If一般现在时主语shall/will+动词原形例句If he comes,he will take us to the zoo.用法：1. 如果主句是一般将来时，从句则用一般现在时。 If it rains（从句）， I will stay at home. Ill go with you if you dont want to go alone（从句）. 2.如果主句含有must, may, can 等情态动词，从句也要用一般现在时。 If you drive too fast, you may have an accident. You must stop

9、if the traffic is red. If you finish the homework， you can go home 如果你作业做完了就可以回家了。 If you want to lose weight you must/should eat less bread. 如果你想减肥，你必须少吃面包。3. 如果主句是祈使句，从句同样要用一般现在时。Dont go and play football if you dont finish your homework.Please call me if he comes next Sunday.练一练：1。如果她早点儿起床，就有时间在家

10、里吃早餐 If she_ _a little earlier, shell have time to eat breakfast at home.2。如果你参加聚会，你将会过得很开心。If you_ the party ,you_ _ a great time.3。如果明天下雨，我们将不去野餐If it _tomorrow, we _ _ for a picnic.4。如果你经常听英文歌，你将会喜欢英语If you often _ _English songs, you_ _English.gets upjoin will haverains wont golisten to will lik

11、e当宾语从句表示不确定或疑问时，由if或whether引导，表示“是否、是不是、能否”等。例如：我想知道他是否住这儿。I want to know if (whether) he lives there.他问我能否帮他。He asked me whether (if) I could help him.4）不能用if，只能用whether的四种情况：a. 在介词后Im thinking of whether we should go fishing.b. 直接与or not连用时I dont know whether or not they will come to help us.c. 在动

12、词discuss后面的宾语从句中We discussed whether we would have a sports meeting next week.d. 宾语从句提前时只能用whetherWhether this is true or not, I cant say.难点链接单音节及部分双音节形容词比较级（- er）和最高级（- est）的规则变化。1. 一般在词尾直接加er/est: fastfasterfastest2. 以e 结尾的单词去e加er/est: latelaterlatest3. 以辅音字母加y结尾的单词，把y改成i, 再加 er/est : earlyearlier

13、earliest4.部分双音节词以及所有三音节词，比较级加more，最高级加most：more slowly，most slowly more carefully，most carefully有些副词的比较等级变化是不规则的。常见的有：原级比较级最高级 wellbetterbestbadlyworseworstmuchmoremostlittlelessleastfarfarther / furtherfarthest / furthest副词比较等级的用法He didnt dance so(as) well as Jim. 他跳舞没有吉姆跳得好a. 同级比较：表示两者在某一方面程度相同时，用

14、“as+副词原形+as”的句式；但表示前者不如后者时，用“not so(as)+副词原形+as”的句式。如；The boys are listening as carefully as the girls. 男生们跟女生们在一样认真地听。b.比较级： My brother did much better in his lessons than I. 我哥哥功课学得比我好多了。表示一方程度比另一方更高时，用“副词比较级+than”的句式。在这一句式中，当than前后的动词相同时，通常用助动词代替后面的动词。该动词或助动词可以省略。副词比较级前常用much., a little, still, even表示“更”，这也可以作为判断比较级的依据。如： I sing better than she (does). 我唱歌比她唱得好。c.最