PETS－2语法讲解(4)

现在进行时
　　现在进行时的基本用法：
　　a. 表示现在( 指说话人说话时) 正在发生的事情。
　　 We are waiting for you.
　　b. 习惯进行：表示长期的或重复性的动作，说话时动作未必正在进行。
　　 Mr. Green is writing another novel.
　　(说话时并未在写，只处于写作的状态。)
　　 She is learning piano under Mr. Smith.
　　c. 表示渐变的动词有：get, grow, become, turn, run, go, begin等。
　　 The leaves are turning red.
　　 It's getting warmer and warmer.
　　d. 与always, constantly, forever 等词连用，表示反复发生的动作或持续存在的状态，往往带有说话人的主观色彩。
　　 You are always changing your mind.
　　典型例题
　　My dictionary ___, I have looked for it everywhere but still___ it.
　　A. has lost, don't findB. is missing, don't find　C. has lost, haven't found　 D. is missing, haven't found.
　　答案D. 前句是一个仍在持续的状态，应用进行时，由于没有找到，其影响仍然存在，应用完成时，瞬间动词用于否定式时可用于完成时。
一般过去时的用法
　　1）在确定的过去时间里所发生的动作或存在的状态。
　　时间状语有：yesterday, last week, an hour ago, the other day, in 1982等。
　　Where did you go just now?
　　2）表示在过去一段时间内，经常性或习惯性的动作。
　　When I was a child, I often played football in the street.
　　Whenever the Browns went during their visit, they were given a warm welcome.
　　3）句型：
　　It is time for sb. to do sth　 "到……时间了"　 "该……了"
　　It is time sb. did sth. "时间已迟了"　 "早该……了"
　　It is time for you to go to bed.　 你该睡觉了。
　　It is time you went to bed.　　　你早该睡觉了。
　　would (had) rather sb. did sth.　表示'宁愿某人做某事'
　　I'd rather you came tomorrow.
　　4) wish, wonder, think, hope 等用过去时，作试探性的询问、请求、建议等。
　　I thought you might have some. 我以为你想要一些。
　一般过去时的用法 (2)
　　比较：
　　一般过去时表示的动作或状态都已成为过去，现已不复存在。
　　Christine was an invalid all her life.
　　(含义：她已不在人间。)
　　Christine has been an invalid all her life.
　　(含义：她现在还活着)
　　Mrs. Darby lived in Kentucky for seven years.
　　(含义：达比太太已不再住在肯塔基州。)
　　Mrs. Darby has lived in Kentucky for seven years.
　　( 含义：现在还住在肯塔基州，有可能指刚离去)
　　注意：用过去时表示现在，表示委婉语气。
　　1）动词want, hope, wonder, think, intend 等。
　　Did you want anything else?
　　I wondered if you could help me.
　　2）情态动词 could, would.
　　Could you lend me your bike?