has是什么时态
英语的时态一直是高考的重点，现在完成时态和过去完成时态也是学生们比较难掌握且不会运用的两个时态，看完陆柒老师的这篇文章，从此告别混乱。
现在完成时态：have done /has done一、同学们要明确一个认知，现在完成时态只与现在有关，强调的是现在、现在、现在！是属于现在时态的范畴。不要再纠结语法书上的关于现在完成时态的定义（自己去看，我在这里不写了）。例如:
He is a clerk in a IT company now, but he _________ a teacher for three years.
A. has been B .was C . had been D. would be
这道题的正确答案是B。是不是有很多同学看到 for three years 这个提示词就选择了A的？题中“他”现在是一家公司的职员，当了3年的老师是过去的事，与现在无关。如果选择A的话，说明现在是老师。
二、记住现在完成时态的提示词。必须记住，因为高考语法填空题型中常考！
recently; recent years; these days/ years; lately; since; for 时间段； in the past few years; ever since; in the last five months; up to now; since then; so far; ever; never, yet; once; twice; already; before; just
注意：这些提示词一般情况下是现在完成时态的标志词，除非有前后文有特殊条件限制，比如上面例题中的 for three years情况。
三、如果句子中没有提示词，但句子意思是表达经历、经验或完成等，也要用现在完成时态。例如：
I have seen the movie.
I haven’t read that book.
He has finished his homework.
过去完成时表示过去的过去，只有两种情况可以用该时态。
一、 句子中有两个以上过去的动作，发生在前面的动作用过去完成时态。例如
The play had already started when we got to the theatre. 我们到剧场时戏已经开始了。
看下面的题:
He ______ in Shanghai University for four years before he went Beijing.
A. studied B. had studied C. has studied D. would study
此题答案是B.
二、有标志词：by 过去的时间、before 过去时间
By the end of June they had treated over 10,000 patients.
到六月底他们已经治疗了一万多病人。
I had finished my homework before supper.我在晚饭前就把作业做完了。
注意：除了以上两种情况外，其他情况都不能用过去完成时态。
1) —Have you known Dr. Jackson for a long time?—Yes, since she ______ the Chinese Society.
A. has joined B. joins C. had joined D. joined
2) I like these English songs and they ________many times on the radio.
A. taught B. have taught C. are taught D. have been taught
3) —I’m sure Andrew will win the first prize in the final.—I think so. He ______ for it for months.
A. is preparing B. was preparing C. had been preparingD. has been preparing
4) By the time he realizes he ______ into a trap, it’ll be too late for him to do anything about it.
A. walks B. walked C. has walked D. had walked
5) We first met on a train in 2000. We both felt immediately that we ______ each other for years.
A. knew B. had known C. have known D. know
6) Years ago we didn’t know this, but recent science _________ that people who don’t sleep well soon get ill.
A. showed B. has shown C. will show D. is showing
7) The country life he was used to _________ greatly since 1992.
A. change B. has changed C. changing D. have changed
8) “Hurry up! Alice and Sue are waiting for you at the school gate.” “Oh ! I thought they _________ without me.”
A. went B. are going C. have gone D. had gone
9） When Alice came to, she did not know how long she _____ there.
A. had been lying B. has been lying C. was lying D. has lain
10） Experiments of this kind _____in both the U.S. and Europe well before the Second World War.
A. have conducted B. have been conducted
C. had conducted D. had been conducted
11） Tom __________ in the library every night over the last three months.
A. works B. worked C. has been working D. had been working
12） After getting lost in a storm, a member of the navy team _____ four days later. (
A. rescued B. was rescued C. has rescued D. had been rescued
13） When I got on the bus, I _____ I had left my wallet at home.
A. was realizing B. realized C. have realized D. would realize
14）She was surprised to find the fridge empty; the child _____ everything! (山东卷
A. had been eating B. had eaten C. have eaten D. have been eating
15） We arrived at work in the morning and found that somebody __into the office during the night.
A. broke B. had broken C. has broken D. was breaking
