you are always changing your mind. 你老是改变主意。
过去进行时
1）概念：表示过去某时正在进行的状态或动作。
2）过去进行时的主要用法是描述一件事发生的背景；一个长动作延续的时候，另一个短动作发生。
3） 常用的时间状语有this morning, the whole morning, all day yesterday, from nine to ten last evening, when, while等。例如：
my brother fell while he was riding his bicycle and hurt himself. 我兄弟骑车时摔了下来，受了伤。
it was raining when they left the station. 他们离开车站时，正下着雨。
when i got to the top of the mountain, the sun was shining. 我到达山顶时，阳光灿烂。
将来进行时
1） 概念：表示将来某时进行的状态或动作，或按**将来会发生的事情。例如：
she'll be coming soon. 她会很快来的。
i'll be meeting him sometime in the future. 将来我一定去见他。
注意：将来进行时不用于表示"意志"，不能说 i'll be h**ing a talk with her.
2）常用的时间状语有soon, tomorrow, this evening，on sunday, by this time，tomorrow, in two days, tomorrow evening等。例如：by this time tomorrow, i'll be lying on the beach.
明天此时，我正躺在海滩上呢。
15. 一般现在时代替一般将来时
when, while, before, after, till, once, as soon as, so long as, by the time, if, in case （that）, unless, even if, whether, the moment, the minute, the day, the year, immediately等引导的时间状语从句，条件句中，用一般现在时代替将来时。例如：
he is going to visit her aunt the day he arrives in beijing. 他一到北京，就去看他姨妈。
16. 一般现在时代替一般过去时
1 ） 书上说"，"报纸上说"等。例如：
the news***** says that it's going to be cold tomorrow. 报纸上说明天会很冷的。
2） 叙述往事，使其生动。例如：
napoleon's army now advances and the great battle begins.拿破仑的军队正在向前挺进，大战开始了。
17. 一般现在时代替现在完成时
1） 有些动词用一般现在时代替完成时，如hear, tell, learn, write , understand, forget, know, find , say, remember等。例如：
i hear （=h**e heard） he will go to london. 我听说了他将去伦敦。
i forget （=h**e forgotten） how old he is. 我忘了他多大了。
2） 用句型 " it is … since…"代替"it has been … since …"例如：
it is （=has been） five years since we last met. 从我们上次见面以来，五年过去了。
18. 一般现在时代替现在进行时。
在here comes…/there goes…等句型里，用一般现在时代替现在进行时。例如：
there goes the bell. 铃响了。
19. 现在进行时代替将来时
1） 表示即将发生的或预定中计划好的活动。例如：
are you staying with us this weekend? 和我们一起度周末好吗？
we are le**ing soon. 我们马上就走。
2） 渐变动词，如get, run, grow, become, begin以及瞬间动词die等。例如：
he is dying. 他要死了。
20.时态一致
1） 如果从句所叙述的为真理或相对不变的事实，则用现在时。例如：
at that time, people did not know that the earth moves. 那时，人们不知道地球是动的。
he told me last week that he is eighteen. 上星期他告诉我他十八岁了。
2） 宾语从句中的，助动词ought, need, must, dare 的时态是不变的。例如：
he thought that i need not tell you the truth. 他认为我不必告诉你真相。
三。巩固练习：
1、i’ ll give the book to him as soon as heback.
2、has the babycrying yet? (stop)
3、i don’ t know whether motherme to beijing next month.(take)
4、she __on her coat and went out. (put)
5、 “what are they doing?” theyready for the sports meeting.” get)
6、the boy asked his mother __him go and play basketball.(let)
7、i’m sorry to keep youfor a long time. (wait)
8、ittake) him half an hour___finish) his homework yesterday.
9、if itan interesting film, we’ll see it tomorrow. (be)
10、they usuallydo) their homework after supper.
11、listen! whosing) in the next room now?
12be) your parents in shanghai last year?
13、mr. yuteach) us maths since 1982.
14、they will h**e a trip to the great wall if itnot rain) tomorrow.
15、li ming oftenlisten) to the radio in the morning.
16、a: “father, may i go out and play football?” b: “you __do) your homework?”
17、all the people in the town are glad __hear) that a famous musician __a concert this saturday evening.( give)
18、our teacher told us if it __not snow) we would visit the science museum the next day.
19、they oftenplay) football in the afternoon.
20、a: what’re you doing dad? b: i___mend) the radio.
21、let’s __carry) the boxes to the house.
22、yesterday she __want) very much to see the film, but she couldn’t __get) a ticket.
23、iwrite) to you as soon as i get to shanghai.
24、mikevisit) several places since he came to beijing.
25、hewrite) four letters to his wife every month.
26、don’ t make any noise, grandmasleep).
27、his auntdo) some cooking when he came in .
28、when theyreach) the station, the train had already left.
29、therebe) a meeting next monday.
30、weknow) each other since our boyhood..
31、sometimes my fathercome) back home late.
32、theyh**e) an english evening next week.
33、i’m very gladhear) that.
34、wei fang isn’t here. shego) to the reading-room.
35、the storyhappen) long ago.
36、theyvisit) the history museum last week.
37、zhang hongmake) many friends since she came to paris.
38、shego) to the cinema with her classmates tomorrow evening.
39、stay here, bag. don’t go out. itrain) now.
40、li pingwrite) a composition every week.
41、the scientistgive) us a talk yesterday.
42、my parentslive) in beijing since 1949.
43、look! the young workershow) the students around the factory now.
44、theybuild) a new bridge over the river next year.
45、the studentsclean) their classroom tomorrow.
46、the windows of our labclean) once a week.
47、our teacherjoin) the party twenty years ago.
48、the boysh**e) a basketball match now. let’s __go) and __watch).
49、shework) in this factory for ten years.
50、 “what makes youthink) i’m a farmer?” the frenchman asked.
四。答案 1. comes
2. stopped
3. will take
4. put
5. are getting
6. to let
7. waiting
8. took … to finish
9. is10. do
11. is singing
12. was
13. has taught
14. doesn’t rain
15. listens
16. h**e … done
17. to hear … will give
18. didn’t snow
19. play
20. am mending
21. carry
22. wanted , get
23. will write
24. has visited
25. writes
26. is sleeping
27. was doing
28. reached
29. will be
30. h**e known
31. comes
32. will h**e
33. to hear
34. has gone
35. happened
36. visited
37. has made
38. will go
39. is raining
40. writes
41. g**e
42. h**e lived
43. is showing
44. will build
45. will clean
46. is cleaned
47. joined
48. are h**ing, go … watch
49. has worked
think
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