八年級下冊語法知識重點

1、八年級下冊語法知識重點1. If 引導(dǎo)的條件狀語從句（1） 當(dāng)主句和從句所表示的是原理、客觀事實、規(guī)則時，主句是一般現(xiàn)在時（包括祈使句和含有情態(tài)動詞can，may，must等），從句也用一般現(xiàn)在時。e.g.1.You must see the doctor if you are ill.如果你生病了，你就必須去看醫(yī)生。（含情態(tài)動詞）2. If you stick a pin into a balloon , it bursts.如果你用針刺氣球，它就會爆炸。（原理）3. Be careful if you cross the road.如果你過馬路，請小心。（祈使句）（2） 在if引導(dǎo)的條件狀

2、語從句中，如果從句談?wù)摰臅r一個有可能發(fā)生的事實及其產(chǎn)生的相關(guān)的結(jié)果，主句用一般將來時態(tài)，從句用一般現(xiàn)在時態(tài)。e.g.1.If it rains tomorrow, we will not go to the zoo.2. If you go to bed earlier, you wont feel tired in the morning.2. 后帶ing和do的動詞seeSee sb do sth看到某人經(jīng)常做某事或做某事的全過程See sb doing sth看到某人正在做某事noticeNotice sb do sth 注意到某人經(jīng)常做某事或做某事的全過程Notice sb doing

3、 sth注意到某人正在做某事watchWatch sb do sth觀察到某人經(jīng)常做某事或做某事的全過程Watch sb doing sth觀察到某人正在做某事hearHear sb do sth聽到某人經(jīng)常做某事或做某事的全過程Hear sb doing sth 聽到某人正在做某事listen toListen to sb do sth聽見某人經(jīng)常做某事或做某事的全過程Listen to sb doing sth 聽見某人正在做某事3. 情態(tài)動詞Should1、 作為情態(tài)動詞，通常用來表示現(xiàn)在或?qū)淼呢?zé)任或義務(wù)，表示“應(yīng)該，應(yīng)當(dāng)”。e.g.Crime should be&

4、#160;punished.        犯罪應(yīng)受懲罰。 二、作為情態(tài)動詞，可以用來表示有較大可能實現(xiàn)的猜測、推論，表示“可能，該(=will probably) ”。     e.g. The headmaster should arrive soon.       校長可能很快就到了。  &#

5、160;     They should be home by now，I think.        我想現(xiàn)在他們總該到家了吧。Exercise: 情態(tài)動詞練習(xí)題 1. Jean _have kept his promise.I wonder why he changed his idea.A.must B.should C. need D.would2.-Could I use your bike?-Yes,su

6、rely you_.A.might B.will C.can D.should3.Its nearly eight o clock.Bruce_be here at any momentA.must B.need C.should D.can4.Tommy,you_play with the knife,you_get hurt.A.wont; cant B.mustnt; may C.shouldnt; must D.cant; shouldnt5.When he was there,he_go to that coffee shop at the corner after work eve

7、ry day.A.would B.should C.had better D.might6.-When can you get the film developed?I need it tomorrow morning.-It _be ready by 8：00.A.can B. should C.might D.need7.-Will you stay for another hour?-Sorry,_.One of my best friends is coming to see me.A.I mustnt B.I cant C.I neednt D.I wont8.Jason shoul

8、dnt_me your secret,but he meant no harm.A.have told B.tell C.be telling D.having told9.-Are you coming for dinner?-Im not quite sure.I_go to my uncles instead.A.must B.would C.should D.might10.-Dont forget to visit me when you come to Beijing.-_.A.I dont B.I wont C.I cant D.I havent11.He ought_have

9、done so even though possible.A.not to B.to not C.not D.never12.Jane_have come to the party,but she _not find the exact time.A.could;could B.might;could C.should;could D.should;would13.So many mistakes in your homework!You_more careful.A.may be B.had to C.would be D.should have been14.Her brother_be

10、at home now,because he was seen playing basketball in the stadium just now.A.mustnt B.neednt C.cant D.shouldnt15.-I cant understand why our boss is late.-He_the early bus.A.could miss B.may have missed C.can have missed D.might miss答案：1-5 BCCBA 6-10 BBADB 11-15 AADCB 4. 動詞+介詞/動詞+副詞動詞+介詞：構(gòu)成的詞組相當(dāng)于一個及物

11、動詞，賓語總是在介詞后面。e.g.I dont much care for the television. 我不是很喜歡電視。動詞+副詞：構(gòu)成的詞組可作及物動詞，也可作不及物動詞。作及物動詞時，賓語的位置有兩種情況：賓語如果是名詞，則可放在副詞后面，也可放在動詞與副詞之間；而如果賓主是代詞，只能放在動詞后面，即動詞和副詞之間。作不及物動詞時，后不帶任何名詞或代詞作賓語。e.g.Something unexpected has turned up.出現(xiàn)了令人意外的情況。5. 后帶to do（動詞不定式）的動詞agree to do sth同意做某事decide to do sth決定做某事ref

12、use to do sth拒絕做某事remember to do sth記得做某事forget to do sth忘記做某事try to do sth盡力做某事want to do sth 想要做某事6. Have to 與mustHave to 表示“不得不”，強調(diào)客觀需要，有人稱、時態(tài)和數(shù)的變化；而must則著重說明主觀看法，表示個人的意志，是情態(tài)動詞，沒有人稱、時態(tài)和數(shù)的變化。E.g.Did she have to pay a fine? 她非得交罰款嗎？I must go there to help the poor.我必須去那兒幫助那些窮人們。（表示說話人自己的看法）在某些不需要強調(diào)

13、這兩種差別的場合，兩者可以互換。e.g.I am afraid we have to / must leave now. 恐怕我們必須得走了。SummaryHave to must表示客觀的需要說話人主觀上的看法，主觀上的必要有人稱、數(shù)、時態(tài)的變化只有一種形式在否定結(jié)構(gòu)中dont have to表示“不必”否定結(jié)構(gòu)中，mustnt表禁止，neednt表示“不必”不能表示推測能表示推測，意為“一定是，肯定是”7. 詞語辨析1 pay, spend, take, cost意義搭配payspendtakecost2 sometimes，some times，sometime與some timesom

14、etimes表示動作發(fā)生的不經(jīng)常性，多與一般現(xiàn)在時連用some times其中time是可數(shù)名詞，有來提問次數(shù)sometime表示某個不確切或不具體的時間，常用于過去時或?qū)頃rsome time表“某一段時間”時，常常修飾延續(xù)性的動作3how often，how long，how soon 與 how many timeshow often“多久一次”，指動作的頻率How often do you go to cinema?Twice a week.how long“（延續(xù)）多長時間 ”，回答用”for.”或”since.”引導(dǎo)的時間狀語How long have you been in Am

15、ercia?For two years.how soon“還要多久（時間）才”，一般用將來時態(tài)，回答用”in.”引導(dǎo)的時間狀語How soon will he be back?Hell be back in an hour.how many times“多少次”，用于詢問次數(shù)，回答用once，twice，three times等How many times have you been here?Four times.e.g.1.How do you exercise?2. How does it take to get to Shanghai from here?3. How is the r

16、iver?4. How is it from here to the park?5. How have you been here? 8. 狀語從句在句中作狀語的從句，分為九種，常見的有時間狀語從句，原因狀語從句，條件狀語從句，結(jié)果狀語從句及目的狀語從句。1Until引導(dǎo)的時間狀語從句Until意為“直到，在之前”。Until 和not.until的區(qū)別e.g.Continue in this direction until you see a sign. 一直朝著這個方向走，直到你看見一個指示牌。I didnt wake up until I heard the alarm clock. 直

17、到聽到鬧鐘響我才醒來。Summary: 2so that引導(dǎo)的目的狀語從句So that是連詞，意為“為的是，以便”。注意so that, in order that 和in order to的區(qū)別。So that/in order that后加從句，而in order to 后加短語。3unless引導(dǎo)的條件狀語從句Unless是“除非，如果不”，相當(dāng)于if.not。e.g.I wont go to the party unless Im invited. 除非我被邀請，否則我不會去參加晚會的。4as soon as引導(dǎo)的時間狀語從句意為“一就”。e.g.He will report bac

18、k here as soon as he arrives. 他一到達就會來這里匯報的。5so.that/such.that引導(dǎo)的結(jié)果狀語從句句型中so是副詞，常用來修飾形容詞或副詞，意思是“如此以至于”，常用句型為：主語+謂語+so+adj./adv/+that從句。Such.that句型中such是形容詞，修飾名詞，意思是“如此以至于”，常用句型為：A.主語+謂語+such+adj.+復(fù)數(shù)可數(shù)名詞+that從句；B.主語+謂語+such+a(an)+adj.+單數(shù)可數(shù)名詞+that從句；C.主語+謂語+such+adj.+不可數(shù)名詞+that從句。由so.that引導(dǎo)的從句可轉(zhuǎn)換成含不定式的

19、簡單句，即可轉(zhuǎn)換為”.enough to.”或”too.to.”。He was so clever that he could understand what I said.He was clever enough to understand what I said.The question is so easy that I can work it out.The question is easy enough for me to work out.The bag is so heavy that she cant move it.The bag is too heavy for her t

20、o move.The girl is so young so that she cant dress herself.The girl is too young to dress herself.9. 過去進行時與when/while引導(dǎo)的時間狀語從句When 當(dāng)?shù)臅r候 while 在期間 before 在之前After 在之后 as 當(dāng)?shù)臅r候 since 自從Until 直到過去進行時結(jié)構(gòu)Was/were+V-ing時間狀語用法表示過去某一時刻用某一階段正在發(fā)生的動作What were you doing this time yesterday?表示某個短暫性動作發(fā)生的背景(主句動作和從句動作都發(fā)生在過去，動作時間長的用過去進行時，短的用一般過去時。）Jim hurt his hand when he was cooking.I met Diana while I was shopping this moring.表示兩個同時持續(xù)的動作I was doing homework while he was listening to music從句區(qū)別When引導(dǎo)的時間狀語從句：While引導(dǎo)的時間狀語從句：10. 感嘆句whatWhat+a/an+adj+可數(shù)名詞單數(shù)（