8B 现在完成时用法

8B Unit 1 Past and present

Grammar 现在完成时

一、现在完成时用来表示之前已发生或完成的动作或状态，但它的影响现在还存在；也可表示持续到现在的动作或状态。其构成： have (has) +过去分词。规则变化的过去分词与过去式的变化一样，在动词词尾加ed; 不规则变化的过去分词见不规则动词表，需要同学记忆。

现以see the film为例将现在完成时的肯定句，否定句和疑问句列表如下：

肯定句：I/You/We/They have seen the film. He/She /It has seen the film. 否定句：I/You/We/They have not/ haven’t seen the film.

He/ She/It has not/hasn’t seen the film.

疑问句：Have I/you/they seen the film? Yes, you/ we/I/they have. No, you/ we/I/they haven’t.Has he/she/it seen the film? Yes, he/ she/ it has. No, he/ she/ it hasn’t.

二、用法：现在完成时既涉及过去，又联系现在。

用法一：表示过去发生或已经完成的某一动作对现在造成的影响或结果。常与just（刚刚），already（已经），never（从来没有），ever（曾经），before（以前），yet（仍然），once（一次），twice（两次），many times（很多次），how many times （多少次），so far（迄今为止），during the past（last）three years（最近三年来）等连用。※

副词的位置：①just常用于肯定句中，放在have / has后，He has just come .

②never表示否定, 放在have / has后, He has never visited the Great Wall.

③ever用于疑问句中,句型为: Have / Has＋主语＋ever ＋过去分词？“…曾经……过吗？”用于询问某人过去的经历。Have you ever been to the farm？④before

用于句末，The woman has never heard of that before.⑤yet 用于句末或not 之后.Has the train arrived yet? No, not yet.⑥already用于肯定句, have / has 之后或句末.We have already finished it.⑦so far用于句首或句末. So far, we have visited the moon.

用法二：表示过去已经开始，一直延续到现在的动作或状态。时间状语有：①for＋表示一段时间的词语I have taught English for 19 years。② since＋表示过去时间点的词语He has been at this school since 1986.③ since＋表示过去的时间状语从句I have lived here since I was born.④ since＋一段时间＋ago. I have known him since 20 years ago.

三、现在完成时态中可以和表示一段时间状语（for，since，how long, all one’s life）连用的动词必须是表示延续的情况或动作的动词，即延续性动词。

如：be，have，know，live，work，study，learn，teach，keep，speak，talk，draw，wait，wear，walk，sleep，drive，write，do，clean等。I have been a teacher for nearly 20 years. How long has he lived here?

四、延续性动词的现在完成时可和包括“现在”在内的（到说话时仍未结束）表示一段时间的状语连用。如this morning，today，this week，these daysHe has been to Beijing three times this year. He has written two letters this morning.（说话时间在上午）He wrote two letters this morning.（说话时间在下午或晚上）

五、英语中还有一些动词的意义决定它们所表示的动作不能延续,只是一瞬间

就结束的动作,这类动词叫做“非延续性动词”，常见的有：come，go，arrive，reach，see，hear，close，open，leave，begin，start，lose，buy，fall，join，die，get up，become，borrow，lend，find，finish，receive等。这些动词可用于现在完成时，说明某个动作的结果还存在，但不能和表示一段时间的状语（how long，for，since）连用。

He has come back.（√）He has come back for two hours.（×）※但在否定句中，非延续性动词也可用表示一段时间的状语来修饰，如I haven’t heard from my father for a long time. We haven’t seen him since 1999.

六、当终止性动词（非延续性动词）与表示一段时间的状语（how long，since，for， all one’s life）相矛盾时,改正错句的方法有如下几种:

（1）用副词ago把现在完成时的句子改为一般过去时.He has come back for two weeks.（错）改为:He came back two weeks ago.（正）I have lost my bike for ten days. （错）改为:I lost my bike ten days ago. （正）

（2）用“It is / has been＋时间＋since＋一般过去时态”句型来改写。He has joined the League for 3 years. （错）It is 3 years since he joined the League.I have bought the book for 5 days. （错）It is 5 days since I bought the book. （正）He has died for 20 years. （错）It is 20 years since he died. （正）（3）用“时间＋has passed＋since＋一般过去时态”句型来改写。He has left home for 20 years. 改为:Twenty years has passed since he left home.He has lost his pen for 2 days. 改为:Two days has passed since he lost his pen.

（4）用系表结构来改写.He has died for 20 years. 改为: He has been dead for 20 years.The factory has opened since 1999. 改为:The factory has been open since 1999.How long has he left? 改为:How long has he been away?

（5）用相应的延续性动词替代非延续性动词。He has bought the book for two weeks. 改为:He has had the book for two weeks.常见的相应转换形式如下:borrow / lend→keep, buy→have, finish / end→be over, arrive /come / go / move / reach /get to→be in /at / be here /be there, begin / start→be on , open →be open , close→be closed, die→be dead , leave→be away（from）,go to school →be in school / be a student, get up→be up, fall asleep→be asleep , fall ill→be ill, get to know→know, lose→be lost, become→be, return / come back / get back→be back, join→be in / be a…member, join the army→be in the army /be a soldier, receive / get a letter→have a letter , catch / get a cold →have a cold, begin to study→study,他参军已有三年.He has joined the army for three years.（错）改为:He has been in the army for three years / since