防辐射服评测英语完成时态
现在完成时结构：主语+have/has+动词的过去分词。
过去完成时结构：had+done。
将来完成时构成：shall/will+have+过去分词。
完成时就是已经完成的时态。
一般用的比较多的是过去完成时和现在完成时。
现在完成时
肯定句：主语+have/has+动词的过去分词+宾语.
否定句：主语+have/has+not+动词的过去分词+宾语.
一般疑问句：Have/Has+主语+动词的过去分词+宾语.
特殊疑问句：特殊疑问词或词组+一般疑问句(have/has+主语+过去分词+其他)
过去完成时
否定形式：had+not+done.
一般疑问句：had放于句首。
将来完成时
被动语态:will have been done
用法 ①表示在将来某一时间之前已完成的动作，并往往对将来某一时间产生影响。
We will have learned 12 units by the end of this term.
到这个学期末，我们将学完12个单元。
②表示推测，相当于”must have done”结构。
You will have heard of this, I guess.
我想你已经听说过这件事了。
③表示某种状态一直持续到说话人所提及的时间。
We will have been married a year on June 25th.
到6月25日我们俩结婚就满1年了。
英语中完成时就是已经完成的时态。包括现在完成时，过去完成时和将来完成时以及过去将来完成时。
完成时态的构成分为两部分：一是助动词，二是实义动词的过去分词。
完成时态的构成分为两部分：一是助动词，二是实义动词的过去分词-ed。
具体来说，用助动词have表示“时”，以表明动作发生的时间是在过去、现在还是将来;用过去分词来表示动作的“态”，以表明该动作已经完成。
延伸阅读
英语完成时态的用法
英语完成时态分为两种，一个是现象完成时，一个是过去完成时，那么完成时的用法先说现在完成时，谓动词的结构是have或 has加动词的过去分词。过去完成时谓动词的结构是had加动词的过去分词。比如说I had finished my homework her。
she has finished her homework。
完成状态下的四种时态
1、现在完成进行时
the present perfect continuous tense
概念：表示某一动作开始于过去某一时间，延续或重复地出现至今，还将延续至将来；
We have been working on this project for over a month now.
It has been raining for two hours.
It seems oil has been leaking from this pipe for some time.
2、过去完成进行时
the past perfect continuous tense
概念：相对过去的某个时刻来说对现在已经有直接影响并且还在进行的动作；
She had been suffering from a bad cold when she took the exam.
John had been asking me the same question for almost 6 times.
I had been looking for it for days before I found it.
3、将来完成进行时
the future perfect continuous tense
概念：表示动作从将来的某一时间开始一直延续到将来某一时间, 并可能继续延续下去；
Vicky will have been working in this School for 12 years by the end of next year.
The play is coming off in August. By then it will have been running for three months.
By the time John retires, Jerry will have been teaching for 10 years.
4、过去将来完成进行时
the past future perfect continuous tense
概念：表示动作从过去某一时间开始一直延续到对于过去来说的将来某一时间，并可能继续下去；
I heard that by May Vicky would have been working here for twelve years.
She told me she would have been teaching in the university for 20 years by that summer.
He said that by the end of the spring term he would have been studying English for three years.
