初中英語if引導的條件狀語從句在 if 引導的條件狀語從句中，if 和條件句位置靈活，可直接放在主句后面，若 if 條件句放句首， 從句后面要加逗號，和主句隔開。還要注意前后時態(tài)一致原則.引導條件狀語從句的連接詞主要有：if(如果）、unless（除非）或 as long as（只要）等。unless在意思上等于if.not。 一、條件狀語從句用法 1、引導條件狀語從句最常用的連詞是if,由if引導的條件狀語從句表示在某種條件下某事很可能發(fā)生。如： If you ask him, he will help you.如果你請他幫忙,他會幫你的。 If you fail in the exam, you will let him down.如果你考試不及格,你會讓他失望的。 另外,if從句還表示不可實現(xiàn)的條件或根本不可能存在的條件,也就是一種虛擬的條件或假設,從句多用一般過去時或過去完成時。如: If I were you, I would invite him to the party.如果我是你,我會邀請他參加聚會。 2、unless = if.not. 除非,若不,除非在的時候 例如：Lets go out for a walk unless you are too tired. =If you are not too tired, lets go out for a walk. Unless it rains, the game will be played.除非下雨,比賽將照常進行。 二、時態(tài)問題 在條件狀語從句中，要注意“主將從現(xiàn)”的規(guī)定，即主句用一般將來時，從句用一般現(xiàn)在時表示將來時。例句：I will come to see you if I have time. 我有時間，我就來看你。三 如果 if 條件句談論的是重復發(fā)生和預示要發(fā)生的情景和事件，則主從句大多用一般現(xiàn)在時態(tài)。如： If bears are in danger ,they attack people.誤區(qū)提醒 if 既可以引導條件狀語從句，表示“如果”，也可以引導賓語從句，表達“是否”。辨別它在這兩種從句中的時態(tài)是我們經(jīng)常容易出錯的地方。另外，if 和unless的用法也需注意。 典型例題： -I wonder if your wife to the party. -If your wife _, so will mine。. A. will go， go B. will go, goes C.goes, will go D. will go, will go 解析：第一句中if表示“是否”，引導賓語從句，用將來時will go；第二句“如果你的妻子去，我的妻子也去”，if引導條件狀語從句，用一般現(xiàn)在時表示將來時。 your wife，單三人稱主語，所以用goes ?？偨YIF引導的 一、表示將來可能發(fā)生的： (1) If sb does sth, sb will do sth = sb will do sth if sb does sth 主句一般將來時 從句一般現(xiàn)在時(2)主句為祈使句或情態(tài)動詞形式If sb does sth, please do sth If sb does sth, sb may(情態(tài)動詞) do sth 二、表必然發(fā)生的If sb does sth, sb/sth does sth = sb/sth do sth if sb does sth 主句一般現(xiàn)在時， 從句一般現(xiàn)在時（相當于when引導的從句）Unless引導的sb will do sth unless sb does sth if sb does not do sth 練習1.He _ (fail) in the exam if he _ (not study) hard.2.Unless you _ (leave) now, you _(be) late.3.We _ (have) a barbecue unless it _ (rain) .4.Hurry up, or you will miss the bus.（同義句轉換） _ you dont hurry up, you _ catch the early bus.5.Study hard, or youll miss fall behind. （同義句轉換） _ you study hard, you_ fall behind.6.If you dont put on your scarf, youll catch cold. （同義句轉換） Put on your scarf, _ youll catch cold.7.I dont know if it_ tomorrow. ）(表是否，用將來時態(tài))If it _ ,I wont go shopping. (rain) （表如果，用現(xiàn)在時態(tài)）8.I want to know if he _(come) tomorrow, if he _(come), I _(give) the massage to him. 9. Please let us know if he _(arrive) tomorrow. 請告訴我們他明天是否會來 Please let us know if he _ (arrive) tomorrow.如果他明天來的話請告訴我們10.Im sure if he _(go) to the party, he_ (have) a great time.11.If the rain _(stop) tonight, we will go to the cinema.12.Ill buy a computer if I _(have) enough money.13.You _(not get) nervous if you _(do ) enough exercise.14.If she _ (be) kind to me , I _(not argue) with her.15.If you _(pay) more attention to that, he _ (not get) injured.16.Mr Li will be mad if we _(break) the rules.17. If it _ (be) cloudy, they _(not go) there by air.18.Shall I say “Hello” when the foreigner _(come) into the classroom?19.Hell get better grades if he _ (study )hard.20. If you work really hard, you _ (be) famous and rich.if 條件狀語從句的時態(tài)練習 一在正確的答案下劃一條線。1.Daina ( will go/go/goes) to Europe if she (will pass/pass/passes) the exams .2. The graduates (will teach/teach/teaches) in the poor village if the Ministry of Education (will agree/ agree/agrees) soon.3. If a UFO (will land/land/lands) in front of me, I (will go/go/goes) in to look for the alien.4. If he (will have/have/has) money, he (will bulid/build/builds) a science lab.5.Dont wait for me if I (am/ will be) late.6.They (wont/dont) go to the beach if it (will rain/rain /rains).7. I (will call/ call) you if he (will stay/stay /stays) at home.8. (Will / Do/ Does) he visit the museum if he (wont / dont/ doesnt) get tired?9. Where (will/ do/does) they live if they (will miss/ miss/ misses) the bus?二、用所給詞的適當形式填空1.If you _(feel) tired, you _ (have) to have a rest.3. If there _(be) fewer trees, there _( be) more pollution.5. If Marcia _(live) alone, she _( keep) a pet parrot.6. Lana _( buy) a new dress if the old one _(be) out of style.7.The twins _(fight) if they_(argue).8. I _(have) a bake sale if I _(need) money for education.9. Peter _( send) me a beautiful souvenir if he _(tour) Spain.10. If Mr Green _(say) I am hard- working, my parents _( feel) glad.11.I _(go) to the beach if it_ ( not rain) this week.12. _they _( have) a match if the P.E. teacher _(be) busy?13.He _(write) a letter to his grandparents if he _(get) his report card this week.14. If she _(get) up late, she _ ( not catch) the early bus.15. Peter _(major) in English if he _(pass) the exams in Peking University.單項選擇（15分）1.If you _ to the party, youll have a great time. A. will go B. went C. go D. going2. It will be a long time _ Peter _ his work. A. since, has finished B. after, finishes C. when, will finish D. before, finishes.3. What will father _ us from Japan? A. take B. bring C. carry D. make 4. Weifang is famous _ kites. A. for B. to C. on D. with5 I _ her the answer if she _me. A. can tell, will ask B. will tell, will ask C. would tell, ask D. will tell, asks6. What are you going to do tomorrow?-Well go to the library tomorrow if it _. A. isnt rain B. rain C. wont rain D. doesnt rain7.Do you know when he will come back tomorrow?-Sorry, I dont know. When he _ back, Ill tell you. A. comes B. will come C. come D. may come 8. What will you do if y