2.It 结构

　　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.