3.完成时是时态测试的重点，注意与完成时连用的句型和时间状语：
(1)by/between/up to/till +过去时间、since、by the time/when +表示过去发生情况的从句，主句用过去完成时。如：
We had just had our breakfast when an old man came to the door.
Between 1897 and 1919 at least 29 motion pictures in which artificial beings were portrayed had been produced.
(表示1919年时已发生的情况)
(2)by +将来时间、by the time/ when +谓语动词是一般现在时的从句，主句用将来完成时。如：
By the time you arrive in London, we will have stayed in Europe for two weeks.
I hope her health will have improved greatly by the time we come back next year.
(3)by now、since +过去时间、in/during/for/over/the past/last few(或具体数字)years/days/months，主句用现在完成时, 但在it is +具体时间since/before这一句型中，主句更多的时候不用完成时。如：
The changes that howe taken place place in air travel during the last sixty years would have seemed completely impossible to even the most brilliant scientists at the turn of the 19th century.
It is four years since John left school.
(4)在It is the +序数词/形容词最高级+that的定语从句中，谓语动词常用现在完成时。如：
It isn’t the first time that I have found myself in an embarrassing situation.
(5)在no sooner…than…, hardly/scarcely…when/before…句型中，主句常用过去完成时。
(6)其他与完成时连用的时间状语：all this while, all this year, for some time, so far, already, before, just, long, yet等。
4.完成进行时指动作在完成时的基础上还要继续下去。如：
The company has been promising a rise in salary for ages, but nothing has happened.
The school board listened quietly as John read the demand that his followers had been demonstrating for.
时态、语态答题思路：
(1)先根据选项的区别点确定考题要点为时态，然后回到题句中寻找给出的或暗示的时间状语，缩小选择范围，进而选出正确答案；
(2)根据谓语动词与句子主语或非谓语动词与其逻辑主语的关系，确定句子是主动语态还是被动语态。
二、不定式
1.不定式做主语
(1)做形式主语的代词：
不定式做主语, 通常用it充当形式主语, 把做主语的不定式短语后置。 如：
It took me only five minutes to finish the job.
To be frank, it is a great relief to have the task fulfilled in so short a time.
(2)引导逻辑主语的介词：
不定式的逻辑主语一般由介词for引导,但下列表示人的性格行为特征的形容词做表语时, 不定式的逻辑主语则由of引导：
absurd, bold, brave, courageous, careful, careless, clever, wise, foolish, silly, stupid, good, nice, kind, thoughtful, considerate, greedy, generous, honest, modest, polite, rude, cruel, selfish, lazy, wicked, wrong。如：
Experts say walking is one of the best ways for a person to stay healthy.
It’s clever of you to have invented such a device.