2.It 结构
1) It is advisable to exercise(拥有) patience in dealing with such complicated situations.

2) It is advisable to place important telephone numbers nest to the phone in case of an emergency.

3) It is biologically reasonable for deer to reduce their cost of living to increase their chances of surviving in winter.

4) It is essential that the increase in production should be geared to (适应) the increase in public demand.

5) It is necessary that young and old people should communicate more with each other.

6) It is thoughtless of some parents to allow their children to watch whatever program is on television.

7) It is incredible(不可思议) that he ate the big cake just in tow bites.

8) It was obvious to everyone that the marriage would sooner or later end in separation if not diverce.

9) It was clear that Dad could do no more than he was doing already.

10) It is certain that fresh air and exercises are more valuable than medicine.

11) It is certain that with determination and hard work you will succeed eventually.

12) It was quite apparent that both sides were making a great effort to win the prize.

13) It was almost impossible for an Indian to gain even a fair education an extremely difficult, as a result, for an Indian to rese high in life.

14) It is easy to fall into bad habits but very difficult to break away form them.

15) It’s not easy to size up (估计) the situation right now. For we are not well informed on recent developments.

16) It is not easy to say exactly what each part of the brain does.

17) It is not wise to change you money into U . S. currency.

18) It was not until about 1600B.C. when the chariot (马拉战车) was invented that the maximum speed was raised to roughly twenty miles per hour.

19) It is only recently that science has begun to give us some idea of how the brain really works.

20) It was not until the century that man realized that the whole of the brain was involved in the working of the mind.

21) It is conflict and not unquestioning agreement that keeps freedom alive.

22) It was in times of crisis that I finally found out what he was really like.

23) It took the human race millions of years to attain that record.

24) It took a mere twenty-year flick(一瞬) of time to double the limit again.

25) It takes (took) sb. some time to do sth.

26) If it takes less time to bring a new idea to the marketplace, it also takes less time for it to sweep through the society.

27) It will take the council a few weeks to judge the situation before it takes any further action.

28) It is well known that many of our problems are caused at least in part by failure to communicate.

29) It is fairly well known that wild animals survive form year to year by eating as much as they can during times of plenty.

30) It is probably less well known that even with their stored fat, wild animals spend less energy to live in winter than in summer.

31) It remains unknown whether there are intelligent beings outside the solar system.

32) It has been pointed out that in 6000B. C. the fastest transportation available to man over.

33) It is now thought that the more work we give our brains, the more w** able to do.

34) It can be argued that such a response may not mean much (有人认为……)

35) It is reported that the electronic industry is going on rapidly in recent year.

36) It is reported that there has been a decrease in the annual birth rate over the last two decades.

37) It is estimated that the total expenses in the trial manufacture of the new products will come to 30,000 yuan.

38) Once it was thought that nighttime dreams interfered with our needed rest.

39) It has been observed that unemployment brings enormous psychological troubles.

40) Even so, it seemed to him that he was part of the whole event.

41) It seems to me that the Americans are a highly mobile people. Most of them like to travel whenever they get the chance.

42) It seemed to me that the only thing that mattered was to get her husband back to her.

43) But it is only because it is my work to do so.

44) It is an encouraging sign that people’s purchasing power(购买力)is on the rise.

45) It is common knowledge that chalk absorbs moisture (湿气) from the air.

46) It might be a way to avoid the indignity of having to ask for money all the time.

47) It used to be a popular belief the we could foretell a person’s future on the basis of the date and time of his birth.

48) It pays in the long run (从长远的角度看……) to introduce new technique.

49) It is time for out symbols of technology to change — to catch up with the quickening changes in technology itself.

50) It has been only twenty-five years since television came to one of people’s pastimes.

51) It may well come as a surprise to learn that not only psychologists but other behavioral scientists have come to accept the positive contribution of work to the individual’s happiness and sense of personal achievement.