① 构成：have / has +过去分词
A. 现在完成时表示一个过去开始的状态或动作持续到现在并可能继续持续下去，常同表示一段时间的状语连用。如so far, up to now, since, for a long time等。
--He has worked as a teacher for many years.
--Up till now, nothing has gone wrong.
B. 现在完成时表示一个过去发生的对现在仍有影响的动作或事件。常与不确定的过去时间状语连用，如yet, just, before, recently等;也同表示频度时间状语连用，如often, ever, never, sometimes, several times等;还可同包括现在时间在内的时间状语连用，如now, today, this morning等。但不能同特定的过去时间状语连用(last year , in 1997等)。
--I have never learned Japanese before.
--We have been quite busy lately (recently).
--We’ll start at 5 o’clock if it has stopped raining by then.
--I shall go to see you when I have finished my homework.
Note: 行为不能持续的瞬间动词(Instantaneous Verb), 如arrive, begin, come, go, start, leave, die, join等通常不能用于这一语法意义，即该类动词在现在完成时中不能与表示一段时间的状语连用。
--He has joined the army for five years. (误)
--He has been in the army for five years. (正)
① 构成：had +过去分词
--David and Jenny had known each other for a long time before their marriage.
--They had got everything ready before the party began.
--He said that he had seen her the day before yesterday.
① 构成：shall / will + have +过去分词
--He will have graduated from high school before his next birthday.
--The shop will have closed already before you get there.
1) 表示状态的动词，如be, seem, appear, become, get等。
He is being a used-car dealer.(误)
He is a used-car dealer.(正)
She is seeming always about to smile.(误)
She seems always about to smile.(正)
2) 表示感官感觉的动词，如see(看见), hear(听见),feel(感觉出), taste(尝出),smell(闻到)等。
The medicine is tasting bitter. (误)
The medicine tastes bitter. (正)
I was seeing a car passing by our house. (误)
I saw a car passing by our house. (正)
3) 表示拥有的动词，如have, own, possess, belong, contain, hold等。
He is owning a luxurious car. (误)
He owns a luxurious car. (正)
The book is belonging to her. (误)
The book belongs to her.(正)
4) 表示思想状况、态度的动词，如believe, think, know, understand, agree, approve, consider, expect, forget, guess, hesitate, hope, imagine, mean, realize, remember, suppose, trust, want, wish等。
I’m thinking that he is right. (误)
I think that he is right. (正)
I’m understanding your feelings. (误)
I understand your feelings. (正)
5) 表示情感、愿望的动词，如admire, appreciate, care, enjoy, like, love, hate, detest, regret等。
He is loving his daughter very much. (误)
He loves his daughter very much. (正)
I’m regretting to say we cannot come. (误)
I regret to say we cannot come. (正)
时态的呼应又称时态一致(Sequence of Tenses)，指的是某些从句里的动词谓语时态必须和主句里的时态保持一致。
--He explained that he had learned Chinese for many years.(现在完成时变为过去完成时)
--He said he had been collecting materials on that subject for a long time.(过去进行时变为过去完成进行时)
--He told me that they would have completed that project by the end of the year.(将来完成时变为过去将来完成时)
--Galileo proved that the earth revolves round the sun.
--The teacher told the students that knowledge is power.
--He said that he joined the Red Army in 1933..