1、Grammar: Present perfect tense1现在完成时: 现在完成时用来表示之前已发生或完成的动作或状态, 其结果的影响现在还存在; 也可表示持续到现在的动作或状态。其构成: have (has) +过去分词2一般过去时与现在完成时的比较： 1) 一般过去时表示过去某时发生的动作或单纯叙述过去的事情, 强调动作; 现在完成时为过去发生的, 强调过去的事情对现在的影响, 强调的是影响。 2) 一般过去时常与具体的时间状语连用, 而现在完成时通常与模糊的时间状语连用, 或无时间状语。 一般过去时的时间状语：yesterday, last week, ago, in1980, in
2、 October, just now等, 皆为具体的时间状语。现在完成时的时间状语: for, since, so far, ever, never, just, yet, up to now, in the past years,等, 皆为不确定的时间状语。3) 现在完成时可表示持续到现在的动作或状态, 动词一般是延续性的, 如live, teach, learn, work, study, know。 一般过去时常用的非持续性动词有come, go, leave, start, die, finish, become, get married等。 例如： I saw this film y
3、esterday. (强调看的动作发生过了) I have seen this film. (强调对现在的影响, 电影的内容已经知道了)He has been in the League for three years. (在团内的状态可延续)He has been a League member for three years. (是团员的状态可持续)(错) Tom has written a letter to his parents last night.(对) Tom wrote a letter to his parents last night. 3 用于现在完成时的句型 1) I
4、t is the first / second time. that结构中的从句部分, 用现在完成时。例如： It is the first time that I have visited the city. This is the first time (that) Ive heard him sing. 注意: It was the third time that the boy had been late.2) This is +形容词最高级+that结构, that 从句要用现在完成时。例如： This is the best film that Ive (ever) seen. 例
5、题1. -Do you know our town at all?-No, this is the first time I _ here. A. was B. have been C. came D. am coming 2. -Have you _ been to our town before?-No, its the first time I _ here.A. even, came B. even, am coming C. ever, come D. ever, have come 注意: 非延续性动词的否定形式可以与表示延续时间的状语连用。即动作不发生的状态是可以持续的。(错)
6、I have received his letter for a month.(对) I received this letter a month ago.(对) I havent received his letter for almost a month.比较since和for: since 用来说明动作起始时间, for用来说明动作延续时间长度。如：I have lived here for more than twenty years. I have lived here since I was born. 注意: 并非有for 时间状语的句子都用现在完成时。I worked here
7、 for more than twenty years. (我现在已不在这里工作。)I have worked here for many years. (现在我仍在这里工作。)注意: 用句型转换的方法, 很容易排除非延续动词在有for/since结构的完成时中的误用。1) (对) Tom has studied Russian for three years. = Tom began to study Russian three years ago, and is still studying it now.2) (错) Harry has got married for six years. = Harry began to get married six years ago, and is still getting married now.显然, 第二句不对, 它应改为 Harry got married six years ago. 或 Harry has been married for six years.