在英语中，不同时间里发生的动作或存在的状态，谓语动词要用不同的形式来表示，谓语动词的这种不同形式称为动词的时态。
英语中有8种基本时态，其中4种现在时态，对应4种过去时态。4种现在时态是：一般现在时态；现在进行时态；一般将来时态；现在完成时态。他们对应的4种过去时态是：一般过去时态；过去进行时态；过去将来时态；过去完成时态。
12-9 时态的呼应
在含有从句的复合句中，主从句的时态要求遵循一定的规则，既保持协调，又相互照应。
1.主句和宾语从句的时态呼应
（1）在含有宾语从句的复合句中，主句是现在时态或将来时态时，宾语从句的谓语动词可用所需要的任何适当的时态。如：
I think Tom is ill today.我认为汤姆病了。（主句一般现在时，从句一般现在时）
I think Tom has gone to the doctor's.我认为汤姆已经去看医生了。（主句一般现在时，从句现在完成时）
I think Tom went to the doctor's yesterday.我认为汤姆昨天去看医生了。（主句一般现在时，从句一般过去时）
（2）当主句的谓语动词是过去时，宾语从句中的谓语动词也要用过去的某种时态。如：
Mr.Smith told me that he would come to our school.史密斯先生告诉我他要来我们学校。（主句一般过去时，从句过去将来时）
Mr.Smith told me that he didn't know the news.史密斯先生告诉我他不知道那个消息。（主句一般过去时，从句一般过去时）
Mr.Smith told me that he had known the news already.史密斯先生告诉我他已经知道那个消息了。（主句一般过去时，从句过去完成时）
注意：
如果从句叙述的是客观真理或不可改变的事实，虽然主句用了过去时态，但从句仍用一般现在时。如：Mr.Smith told me that children under 18 in his country cannot buy alcohol.史密斯先生告诉我在他的国家18岁以下的孩子不能买酒。
2.主句与状语从句的时态呼应
在含有时间状语从句和条件状语从句的复合句中，从句用一般现在时，主句要用一般将来时，祈使句或含有情态动词的句子。如：
You'll make progress if you keep working hard.如果你继续努力你就会取得进步。
Don't get off the bus until it has stopped.直到车停稳再下车。
3.主句与定语从句的时态呼应
在含有定语从句的复合句中，主句的时态有时也决定从句的时态。如果主句的时态是现在时态，从句可根据实际需要确定时态，如果主句用了过去时态，定语从句一般也用过去时态。如：
This is the person I met yesterday.这就是昨天我遇见的那个人。
This is the person who will give us a lecture tomorrow.这就是明天要给我们作报告的那个人。
This was the person who would give us a lecture the next day.这就是第二天要给我们作报告的那个人。
【中考速递】
1.[上海中考考题] This medicine _____ millions of people's lives since it was put into use.
A.is saving B.will save C.has saved D.had saved
2.[北京中考考题] — Where did you go last weekend？
— I _____ to the Great Wall.
A.go B.went C.will go D.have gone
3.[云南昆明中考考题] Look！A dog _____ a blind man across the road.
A.leads B.lead C.is leading D.led
4.[吉林中考考题] Steve _____ TV in the living room when his mother came in.
A.was watching B.watches C.is watching
5.[河南中考考题] Everyone wants to reach the top of the mountain，but all the happiness happens while you _____ it.
A.climb B.climbed C.are climbing D.have climbed
6.[山东济南中考考题] — Does Jimmy still work as a driver？
— No.He has _____ for two years.
A.left the company B.gone to Shanghai
C.studied in college D.lost his job
7.[河北中考考题] Just go down this road and you _____ the library next to the bank.
A.see B.saw C.have seen D.will see
8.[湖北武汉中考考题] — Sorry，Tom.I can't find the book you _____ me.
— It's OK.I don't need it any more.
A.lend B.have lent C.will lend D.lent
【答案点拨】
1.答案：C 句意：自从这款药品投入使用以来，它挽救了许许多多人的生命。由时间状语since it was put into use可知，句子用现在完成时，故选C。
2.答案：B 句意：“你上周去哪了？”“我去长城了”由last weekend 可知句中的谓语动词用一般过去时。故选 B。
3.答案：C 句意：看！一只狗正带领着一个盲人过马路。由句首的Look可知句子用现在进行时，故选C。
4.答案：A 句意：当妈妈进来时，Steve正在起居室看电视。When引导时间状语从句用一般过去时，主句用过去进行时。故选A。
5.答案：C 句意：每个人都想到达山顶，但所有的快乐都发生于你在攀爬的过程中。while引导的时间状语从句用进行时，故选C。
6.答案：C 句意：“吉米仍然是一名司机吗？”“不。他已经在大学里学习两年了。”由for two years可知用完成时，动词要用延续性动词。故选C。
7.答案：D 句意：沿着这条街走，紧挨着银行你会就看到图书馆。在“祈使句+and+陈述句”结构中，陈述句要用将来时，故选D。
8.答案：D 句意：“真抱歉，汤姆，我找不到你借给我的那本书了。”“没关系，我不再需要它了。”由句意可知，“你借给我的那本书”是过去发生的事情，用一般过去时。故选D。
【语法专练 体验中考】
1.[云南考题] — Can John play soccer with us，Mrs.Black？
— One moment，please.He _____ on the phone to his cousin.
A.talks B.talked C.talking D.is talking
2.[山东济南] Sun Hai _____ his mother make dinner when his father got home from work.
A.was helping B.helps C.helped D.is helping
3.[广东考题] School violence（暴力）_____ much attention of the whole society and people are calling the government to make laws against it as early as possible.
A.drew B.will draw C.has drawn D.was drawing
4.[湖北武汉] — Who is that lady？
— She's Miss Green.She _____ us music，and she is so good.
A.taught B.teaches C.will teach D.is teaching
5.[呼和浩特] — I have to be off right now.
— What a pity！I _____ you could stay a little longer with us.
A.thought B.am thinking C.think D.have thought
6.[江西考题] The water _____ dark and dirty.It's no longer safe to drink.
A.become B.has become C.will become D.was become
7.[青海考题] — It's a great pity that the famous football player has gone to another club.
— Don't worry！They _____ another top star recently.
A.buy B.bought C.have bought
8.[黑龙江哈尔滨] — Could you tell me where you found Miss Gao just now？
— Certainly.In the principal's office.They _____ happily at that time.
A.are talking B.have talked C.were talking
9.[江苏镇江] The engineers _____ a new computer in our classroom the whole yesterday morning，so we had our classes in the school hall.
A.were fixing B.fixed C.have fixed D.are fixing
10.[湖北荆州] — Are you going to watch “Running Man” tonight？
— No！I _____ it with my parents only once.I don't think it's exciting.
A.see B.have seen C.will see D.am seeing
11.[辽宁沈阳] I think it is true that Jill _____ to work today because she is on a trip.
A.has come B.didn't come C.is coming D.will not come
12.[湖南张家界] — _____ you ever _____ the history museum，Paul？
— No，I haven't.
A.Do；visit B.Did；visit C.Have；visited
13.[湖北黄冈] — Where are you going，Bob？
— To go hiking.Eric _____ for me at the school gate！
A.was waiting B.waits C.waited D.is waiting
14.[江西考题] — May I speak to Mrs.Black？
— Sorry，Mum can't come to the phone now.She _____ a shower.
A.has B.had C.is having D.was having
15.[湖北黄石] Many scientists believe that robots _____ able to talk like humans in 50 years.
A.were B.are C.will be D.have been
16.[天津考题] — What a nice watch！How long _____ you _____ it？
— For just two weeks.
A.will；buy B.have；had
C.were；having D.did；buy
【答案速递】
1.D 2.A 3.C 4.B 5.A 6.B 7.C 8.C 9.A 10.B 11.D 12.C 13.D 14.C 15.C 16.B
