文档介绍：英语16种时态
英语共有十六种时态, 其表现形式以下(以study为例)
通常时
进行时
完成时
完成进行时
现在
study
studies
am studying
is studying
are studying
have studied
has studied
have been studying
has been studying
过去
studied
was studying
were studying
had studied
had been studying
未来
shall study
will study
shall be studying
will be studying
shall have studied
will have studied
shall have been studying
will have been studying
过去未来
should study
would study
should be studying
would be studying
should have studied
would have studied
should have been studying
would have been studying
 
时态（Tense）是表示行为、 动作和状态在多种时间条件下动词形式。 所以, 当我们说时态结构时候, 指是对应时态下动词形式。
1. 通常现在时
英语时态分为16种: 通常现在、 通常过去、 通常未来、 过去未来时, 和这四者进行时、 完成时和完成进行时。
使用方法: A) 表示现在发生动作、 情况、 状态和特征。
B) 习常见语。
C) 常常性、 习惯性动作。
例: He always helps others. （她总是帮助她人。 ）
D) 客观事实和普遍真理。 尤其要注意, 假如前后文不是通常现在时, 则无法保持   主句、 从句时态一致。
E) 表示一个按要求、 计划或安排要发生动作, （仅限于一些表示“来、 去、 动   、 停、 开始、 结束、 继续”等动词 ）能够和表示未来时间状语搭配使用   。 常见使用方法是: 飞机、 火车、 轮船、 汽车等定时定点运行交通方法。
例: The next train leaves at 3 o'clock this afternoon.
（下一趟火车今天下午3点开车。 ）
How often does this shuttle bus run? （这班车多久一趟？）
F) 在时间和条件状语从句里常常见通常现在（有时也用现在完成时）表示未来事   情。
例: When you have finished the report, I will have waited for about 3       hours.（等你完成这份汇报时候, 我就已经等了快要3个小时了。 ）
2. 现在进行时(be doing)
使用方法: 现在正在进行动作。
3. 现在完成时(have done)
使用方法: A) 表示动作到现在为止已经完成或刚刚完成。
例: I bought a new house, but I _________ my old one yet, so at the moment I have two houses.
A) didn't sell B) sold C) haven't sold D) would sell
答案是C) haven't sold。
B) 表示从过去某时刻开始, 连续到现在动作或情况, 而且有可能会继续延续下去。 此时常常见延续性动词。 时间状语常见since加一个过去时间点, 或for加一段时间, 或by加一个现在时间。
例: Great as Newton was, many of his ideas ___________ today and         are being modified by the work of scientists of our time.
A) are to challenge C) have been challenged
B) may be challenged D) are challenging
全句意思是: “即使牛顿是个伟大人物, 但她很多见解直到今天还在受到挑战, 而且被现代科学家工作所修正。 ”challenge是及物动词, 在本句中应该是被动语态; 其动作延续到今天, 所以要用现在完成时态。 可见答案是C) have been