在英语越来越普及的21世纪，英语水平的高低已经成了大学生是否能找到好工作的评定标准。为帮助大学生掌握权威的英语知识。特提供以下资料：
四级常考的重点时态
英语共有16种时态，在CET-4语法测试中，时态是一个常测项目，也是一个必测项目。
测试重点有：现在完成时，现在进行时，现在完成进行时，将来完成时，过去完成时，过去进行时，一般将来时。
利用时间状语的信息提示
时态与时间状语之间存在一定的呼应关系。时间状语可以决定时态。时间状语常出现在句首或句尾，有时也出现在谓语动词前后。
标志完成时态的时间状语
Ever since, since, since then, by then, by now, by the end of, by the time, when, before, for, so far, up till now, for, in the past few days, in the past / last few years
标志进行时态的时间状语
Now, right now, at the moment, yesterday afternoon, last Sunday, just now, this time tomorrow
标志将来时态的时间状语
Tomorrow, tomorrow morning, soon, next, in two days, in the year 2050, in 10 years’ time, some day in the future,
Examples
1. Ever since the family moved to the suburbs last year, they ____ better health.
A. could have enjoyed B. have been enjoying C. had enjoyed D. are enjoying
2. Since then, I ____ the mail.
A. am expecting B. have been expecting C. expected D. was expecting
3. You should have put the milk in the ice-box; I expect it ____ undrinkable by now.
A. became B. had become C. has become D.become
4. When he hurried to the airport, he found, to his great disappointment, his ticket and passport ___ at home.
A. were left B. had left C. to have been left D. had been left
5. By the time you get to Beijing tomorrow, I ___ for Shanghai.
A. am leaving B. shall have left C. will leave D. have already left
6. It is reported that by the end of next month the bridge ____.
A. will be built B. has been built C. will have been built D. will have built