举例

举例
举例

举例
1.现在完成时的"完成用法"
现在完成时的"完成用法"指的是动作发生在过去某一时刻并已结束,但该动作对现在产生了影响,与现在情况具有因果关系.
例如：He has turned off the light.他已把灯关了.(动作结束于过去,但说明的是现在的情况--灯现在不亮了.)
现在完成时"完成用法"的特点是动作不延续,因此,该时态只能与表示不定的过去时间状语(如：already,yet,before,recently等)、频度时间状语(如：never,ever,once等)、包括现在时刻在内的时间状语(如：this morning ／ month ／year...,today等)连用.
例如：Have you found your pen yet?你已找到你的钢笔了吗?
2.现在完成时的"未完成用法"
现在完成时的"未完成用法"指的是动作开始于过去某一时刻,一直延续到现在,或可能还要继续下去.
例如：He has lived here since 1978.自从1978年以来,他一直住在这儿.(动作起始于1978年,一直住到现在,可能还要继续住下去.)
I have been in the army for more than 5 years.我在部队已经呆了五年多了.(动作开始于5年前,一直延续至今,有可能还要继续下去.)
此种用法的句中常需一个表示一段时间的状语(由since或for引导),或表示与现在时刻相连的时间状语(如：up to now,so far)等.
例如：I have heard nothing from him up to now.到目前为止我没有他的任何消息.
注意：(1)现在完成时的未完成用法只适用于延续性动词,不可用于终止性动词,即瞬间完成或延续时间很短的动词.如：come,go,arrive,leave,join,become,die等.
(2)现在完成时常见两种句型：
①主语＋have / has been＋for短语
②It is＋一段时间＋ since从句
例如：He has been in the League for three years.或It is three years since he joined the League.他入团已三年了.

过去做的事影响到现在
John has gone ( go ) sailing. He will be back in a week. 现在完成时

现在完成时表示过去开始，但持续到现在的动作，或过去发生的动作，对现在留下后果或影响。常和for+一段时间，already, ever, never, just, yet, in the past few years/ over the last thirty years, so far, up to now,等状语连用
【例如】
Most college students ha...

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现在完成时表示过去开始，但持续到现在的动作，或过去发生的动作，对现在留下后果或影响。常和for+一段时间，already, ever, never, just, yet, in the past few years/ over the last thirty years, so far, up to now,等状语连用
【例如】
Most college students have learned English for more than six years. Great changes have taken place in China in the past few years.I have never been abroad up to now.*表示短暂行为的动词不能和延续性时间状语连用。
【例如】
I have been back from England for over two weeks.或It has been over two weeks since he came back from England.We couldn't say: I have come back from England for over two weeks.He has been in the army since 1998. We couldn't say: He has joined the army since 1998.

收起

现在完成时表示过去某一点时间所发生的事情直到现在已经完成或还在延续的动作。
For example
He has already finished his homework.
即have/has+done
这可是我自己辛辛苦苦总结的，给点面子