一时态（02.11.修改） 英语中共有16种时态，我们并不一一赘述。这里我们只讲容易用错的、也是经常出现在试卷上的时态方面的问题。只要同学们掌握了我们所讲的知识就能会做题，做对题。 .“现在时”中应注意的几个问题1. 如果说的是将来的事，主句用将来时，状语从句用现在时。状语从句常由以下连词引导：if, in case, when, as, as soon as before, until, unless, who(what/ when/ where)ever, no matter who(what/ when/ where), etc. If he comes, Ill give it to him. Ill stay here until he promises to do as I ask. You wont pass the exam unless you work hard. Ill begin the dictation when you are ready. No matter where you go, youll find Coca-Cola. No matter how much it costs, Ill buy it. （第1. 2. 3. 4. 5. 6.题） *几个特殊的副词、名词短语也可引导状语从句，所用时态同上。 the moment immediately the minute = as soon as instantly = as soon as the instant directly every time = whenever/ no matter when the next time = next time when each time The children are to do their homework the moment they arrive back from school. The machine starts the minute the button is pressed. Tell me immediately you have any news. Please be sure to telephone me the next time you come.(第7. 8.题) 1）如果强调从句动作在先，主句动作在后时，从句可用完成时。（既从句动作发成之后，才开始主句的动作。） When he has sold all the newspapers, hell go home. The postman cannot reach the house until the snow has melted.2）now that从句常表示已经发生的动作，在从句动作已经发生的前提下才开始主句的动作，故该从句常用完成时。 Now that the rain has stopped, lets go at once. Now that youve got a chance, you might as well make full use of it.（第9. 10.题）3）如果if条件从句出现if sb. will/ would,表示意愿，“如果某人愿意”will、would是情态动词。 If you will take off your clothes, we will fit the new clothes on you.如果你愿意脱掉身上的衣服，我们就把新衣服给你穿上。（从句的will是情态动词，主句的will是助动词，表将来时） If you will only do this, you may find out why people are dissatisfied and understand the revolution that is threatening France. 只有你肯这样做，你就会发现老百姓为什麽会不满意，你就会理解正在威胁着法国的革命。4）if、when引导的宾语从句表达将来的动作时，要用将来时。 I cant tell you if itll rain tomorrow. Do you know when they will arrive?5）一些关系代词、关系副词或连词引导的从句中也可以用现在时表示将来的动作。 Well drive faster than you do. She will probably be on the same plane as I am. Ill have a good time whether I win or lose.2. 以下句型从句用现在时表达将来的动作 long It will (not) be hours before sb. do sth. years It will be long before we meet again. It will be hours before the rain stops. But it will be more than 100 years before the country begins to look as it did before. . 完成时1. 以下句型从句用现在完成时 This the first (second, third fourth) sth.That is the only sth. (that) sb. have done sth.It the best (worst最高级) sth. This is the third pair of shoes youve worn out this year. It is the only party that Ive really enjoyed in my life. It is one of the most interesting books that Ive ever read. * 这里指截止到目前为止的情况，如果说截止到过去的某一时间为止，用过去完成时。 She understood what I was talking about, even though it was the first time we had spoken together. 2. 有以下时间状语的句子用现在完成时 for years during the past/ last year (two, three, four, few/ several) months over weeks in In the past few years great changes have taken place in computers. That has been my life for these ten years.3. since句子里的时态问题 1）作介词用时，和过去的时间搭配，句子用现在完成时 Paper has been made in America since 1690. since ago作状语，句子用现在完成时 Mary is in New York. She has been there since six days ago. ever since 作状语，句子用现在完成时 He fell off his horse a week ago and has been in bed ever since.2）作连词用时，从句用过去时，主句用现在完成时 Weve been friends since we met at school. He has worked there since it opened in 1989. （第12. 13.题）4. 瞬间动词的注意事项 常见的瞬间动词：go, come, enter, arrive, leave, die, marry, join, buy, borrow, get up, catch a cold, get married, etc.这类动词表示的动作一发生就马上结束，故用在完成时中不能和表示动作延续的时间状语连用。 错 He has left for three days. 对 He has been away for three days. 或：It is + 一段时间 + since sb. did (瞬间动词)sth. has been It is/ has been three days since he left. It is more than half a year since I entered college. *如果表达截止到过去的某个时间为止的动作，用以下句型： It was + 一段时间 + since sb. had done (瞬间动词)sth. I said that it was at least 10 years since I had enjoyed a good drink.5. by短语作时间状语的注意事项 1）“by”和过去的时间连用时，句子用过去完成时；和将来的时间连用时，句子用将来完成时。 By 1985, he had taught that course in that school for 10 years. By the end of next year the teaching building will have been completed. (15. 16. 17.18. 19.题)2）by the time作连词引导时间状语从句。（1）如果说的是过去的事情，从句用过去时，主句用过去完成时 By the time he was ten, he had already built himself a chemistry lab. By the time he was fourteen years old, he had learned adva