单词有哪几种时态？
一、 一般现在时：
用动词原型表示，但单数第三人称后要加-s，在词尾加-s时要注意：
1． 一般情况：加-s 例：reads，writes，says
2． 以s，x，ch，sh收尾的词加-es 例：teaches，washes，guesses
3． 以辅音字母+y结尾的词变y为i再加-es 例：try—tries，carry—carries。
这个时态的疑问句一般以句首加助动词do，does构成。句中动词要用原型动词be提前：
do you know it？
are you students？
does she have a pen？
1．一般现在时表示经常性或习惯性的动作：
we always care for each other and help each other。
they cycle to work every day。
2．现在的特征或状态：
he loves sports。
do you sing？a little。
i major in english。
3． 遍真理：
light travels faster than sound。
two and four makes six。
the moon moves round the earth。
有些表示状态和感觉的动词常常可用于一般现在时：be，love，like，hate，want，hope，need，prefer，wish，know，understand，remember，believe，recognize，guess，suppose，mean，belong，think（以为），feel，envy，doubt，remain，consist，contain，seem，look（看起来），see，fit，suit，owe，own，hear，find，suggest，propose，allow，show（说明），prove，mind（在意），have（有），sound（听起来），taste（尝起来），matter，require，possess，desire等等。
i feel a sharp pain in my chest。
the soup contains too much salt。
you see what i mean？
the coat fits you very well。
how do you find the book？
有些表示动作的动词间或可用于这一时态，表示现刻的动作，由于动作持续时间机短，用于进行时不自然：
i send you my best wishes。
i salute your courage。
now i extend my heartfelt thanks to you。
在口语中这个时态用来表示一个按规定、计划或安排发生的情况（这是都有一个表示未来时间的状语）：
when do the train leave（stop at jinan）？
the plane take off at 11 am。
tomorrow is saturday。
is there a firm on tonight？
但这只限少数动词，如begin，come，go，leave，sail，start，arrive，return，dine，end，stop，depart，open，close，be等。另外，在时间或条件从句中，将来动作或状态多用这一时态表示：
tell her about that when she come。
turn off the light before you leave。
we‘ll start as soon as you are ready。
在口语中，这个时态间或可以用来表示一个已经发生的动作（这个动作发生的时间在说话人脑中处于很不重要的地位）：
they say xiao wu is back。is that true？
xiao yu tells me you‘re going abroad。
oh，i forget where he lives。
yes，you answer quite well。
此外一般现在时还多用于报刊、电影、电视解说等其他几种情况。
二、 现在进行时
现在进行时用助动词be的人称形式加现在分词构成，它的肯定、否定、疑问形式如下：
i am working。
i am not working。
am i working？
现在进行时主要表示现在或现在这一阶段正在进行的动作。
where are they having the basket-ball match？
they are putting up the scaffolding。
he‘s showing a foreign guest round the city。
在不少情况下，表示正在进行的动作的汉语句子，并没有“正在”这样的字，在译为英语时却必须用进行时态：
how are you getting on with the work？
the work is going fairly smoothly。
you are making rapid progress。
it is blowing hard。
who are you waiting for？
whenever i see her，she is working in the garden。我每次看到她时，她总是在花园里干活。
在一般现在时所列的表示状态和感觉的动词，一般不能用于进行时态，因为他们不能表示正在进行的动作。但如果词义转变，能表示一个正在进行的动作，就能够用于进行时态，试比较下面的句子：
do you see anyone over there？你看到那里有什么人吗？
are you seeing someone off？你在给谁送行吗？
i hear someone singing。我听见有人唱歌。
they are hearing an english talk？他们在听一个英语报告。
what do you think of it？你觉得这怎么样？
what are you thinking about？你在想什么？
另外，表示无法持续动作的动词，一般不宜用于进行时态，但有些可以用于这个时态表示重复、即将等：
he is jumping up and down。她一上一下地跳着。
the train is arriving。火车就要进站了。
the old man is dying。老头病危了。
现在进行时有时可用来表示一个在最近按计划或安安排要进行的动作（这是多有一个表示未来时间的状语）：
we are leaving on friday。
are you going anywhere tomorrow？
a foreign guest is giving a lecture in english this afternoon。
xiao hong！coming。
who is interpreting for you？
we are having a holiday next monday。
但这仅限于少量动词，如go，come，leave，start，arrive，lunch，return，dine，work，sleep，stay，play，do，have，wear等。
另外，“be going+不定式”这个结构经常用来表示即将发生的事或打算（准备）做的事：
i am afraid it is going to rain。
it is going to be rather cold tomorrow。
she is not going to speak at the meeting。
在这个结构中过去有许多人不赞成用go和come这两个动词，感到很别扭，主张不说are you going to go anywhere tomorrow？而说are you going anywhere tomorrow？不说is she going to come？而说is she coming？但现在在这种结构中用两个动词的人越来越多，这种用法基本上被大家接受了。
此外，在时间和条件状语从句中，间或也可用现在进行时表示将来的情况或一般情况：
do not mention this when you are talking with him。
remember that when you are taking a rest，some else is always working。
if she is still sleeping，do not wake her up。
现在进行时有时用来代替一般现在时，表示一个经常性动作或状态，这是或是为了表示一种感情（a）如赞叹、厌烦等，或是为了强调情况的暂时性（b）。
a． how are you feeling today？（比how do you feel today？更显亲切）
xiao hua is doing fine work at school。（比xiao hua does fine work at school。更富赞美）
he is always thinking of his work。表赞许
he is constantly leaving his thing about。她老是乱扔东西。（表不满）
he is always boasting。他老爱说大话。（表厌烦）
b．he is sleeping in the next room now。他现在现在是在隔壁房间睡了（不再原来房间睡了）。
the professor is typing his own letters while his secretary is ill。
where is he working？他现在在那里工作？（可能刚换工作）
for this week we are starting work at 7：30。
he is walking to work because his bicycle is being repaired。
be间或可用于进行时态，表示一时的表现：
you are not being modest。
he is being silly。
she is being friendly。
xiao hong is being a good girl today。
do not talk rot。i am being serious。
注： 在there和here引起的句子中，常可用一般现在时代替现在进行时：
here comes the bus。（=the bus is coming.）
there goes the bell. (=the bell is ringing.)
在某些情况下两种情况都可以用，没有多少差别：
i wonder (am wondering) how i should answer then.
does your leg hurt? (is your leg hurting?)
it itches (is itching) terribly.
my back aches (is aching).
i write (am writing ) to inform you.
未完待续。。。
(发帖时间:2004-01-06 19:51:16)
---3dnow外语学习成员
三、 一般将来时
一般将来时由助动词shall或will加动词原型构成，shall用于第一人称，will用于第二、三人称。这个时态的肯定、否定及疑问机构可表示如下：
i shall go.
i shall not go.
shall i go?
除英国以外的说英语的国家，在陈述句中，即使在第一人称一般也用will,在英国也有这种趋势，在口语中常紧缩为i’ll.
一般将来时表示将要发生的动作和情况：
i will (shall) arrive tomorrow.
will you be busy tonight?
the agreement will come into force next spring.
we won’t (shan’t) be free tonight.
有时表示将来的时间状语，有时没有时间状语，这时要从意思上判断是否指未来的动作或情况：
i will think it over.
who will take the chair?
will she come?
they won’t object it.
在以i 或 we 作主语的问句中，一般用shall，这时或是征求对方的意见（a）,或是询问一个情况（b）:
a. shall i make a fair copy of it?
which book shall i read first?
where shall we meet?
b. shall we have any classes tomorrow?
when shall we have the rehearsal?
shall i be able to find them there?
在这类问句中，近年来也有不少人用will，特别是美国。
what will we do?
how will get there?
which will i take?
注意在时间或条件状语从句中，一般不能用将来时态，而用现在时态代替：
i’ll let you have the book when i’m through.
they’ll fight till they win complete victory.
i’ll be round to see you if i have time tomorrow.
注：在两种情况下条件从句可以用一般将来时：
1． 表示愿望：
if they won’t cooperate, our plan will fall flat.
2.主句的谓语表时现在的情况：
if he won’t arrive this morning, why should we wait here。
表示将要发生的动作或情况，除了一般将来时外，还有一些其他结构和时态：
1． be going +不定式（表打算、准备作的事或即将发生或肯定要发生的事）：
we ‘re going to put up a building here.
how are you going to spend your holiday?
who is going to speak first?
2. be +不定式（表示按计划安排要发生的事或用来征求对方的意见）：
when is the factory to go into production?
the line is (going) to be opened to traffic next week.
am i to (=shall i ) go on with the work?
3.一般现在时（限于某些动词，表示按计划或时刻要发生的事）：
school finishes on january 18th.
we get off at the next stop.
when does the winter vacation begin?
4.现在进行时（限于某些动词，表示按计划安排要发生的事）：
we are having an english evening tonight.
they are playing some folk music next.
i am talking the children to the zoo (on sunday ).
在单纯表示将来情况，特别是谈一连串的事情或在带时间或条件状语从句的句子中，谓语多用将来时：
next term i will try to do better. i’ll speak more english and do more reading-aloud.
he’ll come to see you when he has time.
he’ll tell you if you ask him.
在表示打算或准备时，如不提时间、条件等，多用be going to这个结构，用一般将来时时很少的，特别是在口语中：
he is going to buy a dictionary.(很少说he will buy a dictionary.)
在谈即将发生的情况时，用be going to 这个结构也多一些。在表示按计划安排要做得事时，用be to 的时候也不少。另外还有将来进行时等时态也可表示将来的动作。
注：be about to 可表示即将作某事
we are about to leave.
he is about to retire.
一般将来时有时还可用来表示一种倾向或习惯性动作：
a drowning man will catch at a straw.
crops will die without water.
oil will float on water.
注：这一时态有时用来表示揣测（a）或容量（b）:
a. that man in the middle will be the visiting minister.
b. the hall will seat 500people.
四、 一般过去时
一般过去时由动词的过去式表示，动词be有was, were两个过去式，was用于第一、三人称单数，were用于其他情况。在构成否定及疑问句时，一般都借助助动词did, 动词be有其独特的疑问及否定形式（基本上和一般现在时一致）。这个时态的三种结构可表示如下：
一般动词：
i worked there.
i did not work there.
did you work there?
动词be:
i was there.
i was not there.
was i there?
一般过去时主要表示过去某时发生的动作或情况（包括习惯性动作）
who put forward the suggestion?
when did she leave?
she often came to help us.
有些情况，发生的时间不很清楚，但实际上是过去发生的，应当用过去时态：
i was glad to get your letter.
what was the final score?
how did you like their performance?
*在谈到已死去人的情况多用过去时：
lao she was a great writer.
my grandmother was kind to us.
有时两种时态都可以用：
brahms was/is one of the greatest representative of german classicalism.
注：在口语中一般过去时有时可用来代替一般现在时，使语气变得婉转一些，例如在下面句子中用一般现在时或一般过去时都可以，但用过去时显得客气一些（带有更多商量的口吻）：
do/did you want to see me?
i wonder/wondered if you could spare a few minutes.
i want/wanted to ask if i can/could borrow your bike.
未完待续。。让大家久等了。第一次自己敲键盘发帖子。好累呀。：（
---3dnow外语学习成员
五、 现在完成时
现在完成时由have的人称形式加过去分词构成。他的肯定、否定及疑问形式如下：
i have read it.
i have not read it.
have you read it?
现在完成时表示现刻以前发生的动作或情况，可以是：
1． 到现在为止的这一时期中发生的情况（可能时多次动作的总和，也可表示状态和习惯性动作）：
we have opened up 200 mu of land this year.
how many pages have you covered today?
i haven’t seen him for many days.
2. 对现状有影响的某一已发生的动作：
the delegation has already left.
i have seen the film many times.
the city has taken on a new look.
注： 这个时态有时还可以表示过去曾发生过一次或多次的情况，也可以说是一种经历：
all our children have had measles.
man’s hairs have grown white in a single might.
he says that he has seen a meteor at some time.
这个时态的基本特点是它和现在有密切的联系，或是讲迄今为止这一段时间的情况，或是讲一个影响现状的动作，这样它不是从时间上就是从后果上和现在联系起来。根据这个特点我们可以判断什么时候用一般过去时，什么时候用现在完成时：
1． 当有一个表示过去某时的状语（包括when）时，不能用现在完成时：
i saw her a minute ago.
just now xiao lin came to see you.
when did you get to know it?
2.当有一个表示到现在为止这段时间的状语时，多用现在完成时：
up till now we have planted over 24,000 fruit trees.
we haven’t had any physical training classes this week.
he has learned a good deal since he came here.
3.在用already, yet, just, as yet, ever, never这类副词作状语时，常可用现在完成时：
this is the second game. they ’ve already won a game.
have you got the plan ready yet? –no, not yet.
i’ve just received a money order.
4.在单独谈一个过去的动作，不涉及它对现在的影响时，通常用一般过去时，如果谈一件已经发生的事，不考虑它是什么时候发生的，而主要考虑对现在的影响，多用现在完成时：
did you get up very early?
has he got up?
what did you have for lunch?
have you had lunch?
i got the news from xiao yu.
i’ve got no news from him.
注： 有since引起的状语时，主要谓语通常用完成时态：
we met in 1972,and have been good friends ever since (then).
it has rained a great deal since you left.
we haven’t seen each other again since them (since we parted in 1952). 但在表示时间长度时可用一般现在时。
l 在使用一个表示状态的动词（如be, seem等）作谓语时，间或也可用现在时态：
it’s ok since i fixed it.
it seems a long time since i was here.
i’m getting interested in china since you came here. 间或用过去时，特别时在口语中。
i lost ten pounds since i started swimming.
在since引起的状语从句中，通常用一般过去时。但间或可用现在完成时：
i haven’t seen him since i have been back.
since i have known her, she has been fond of sports.
有时同样一句汉语，由于使用场合不用，译成英语时可能需要不同时态：
has xiao yang come?
did xiao yang come?
how many people have gone to the factory?
how many people went to the factory?
we haven’t invited him.
we didn’t invite him.
有时同样一个动作，也随着说话的意图不同而用不同时态表示：
has he gone to town? how did he go there? 后一句谈动作本身，与现在无联系。
have you had your lunch? where did you have it？ 你吃中午饭了吗？在那吃的？
has she left? why did she leave so early?
某些动词的现在完成时刻表示一直持续到现在的状态：
how have you been (recently)?
the conference has lasted five days.
we’ve known each other since we were children.
特别是动词be，是常常这样用的：
he’s been back for three days. （不能用has come back）
she has been a teacher for ten years. (不能说has become)
he has been in college for a year. (不能说has entered)
由于come, become, enter和get up 等动词都只代表一个短暂的动作，不能代表一个延续的状态，这是需要用be来表示延续的状态：
另外有少数动词（主要是work, study, teach, live等）可用于现在完成时表示一直持续到现在的一个动作：
how long have you worked here？
she has taught english for many years.
we’ve lived here for quite a few years.
但大多数动词不宜这样用，而需用现在完成进行时。
注：have been (to)长可用来表示“到过某地”或“刚去做过某事”
have you ever been to xi’an?
xiao liu has just been here.
we’ve been here(there)many times.
l 现在完成时还可用在表示时间或条件的状语从句中，表示将来某时业已完成的动作：
i’ll go and see the exhibition as soon as i have got the recorder fixed.
we’ll start at five o’clock if it has stopped raining by then
i will gibe my opinion when i have read the book through.
这利用“现在完成时”时表示这动作将在另一动作之前完成。如果两个动词同时发生，或几乎同时发生，（也就是说一个动作紧接着另一个动作），一般就不用这个时态：
i’ll let you know as soon as i hear from her.
she’ll write you when she gets there.
在这样的情况下（特别是当我们用的是get, arrive, see, hear, leave, return 等代表迅即完成的动作的动词时），多用一般现在时。有时两种时态都可以用：
we’ll leave as soon as it stops(has stopped) raining.
i’ll tell him after you leave (have left).
注：have got 形式上时现在完成时，却和have时同一个意思：
she has got (=has) a slight temperature.
have you got (=do you have) any sisters?
另外，现在有一种倾向，特别是在美国，在随便谈话时，常用一般过去时代替现在完成时：
i saw it already (=i have seen it already).
did you return the records yet （=have you returned the records yet）？
i just come back (=i’ve just come back).