四种常用时态
1．一般现在时
（1）表示经常发生的动作或事情，通常用 “usually, often, every day, sometimes，always, never”等词。
（2）基本结构：
I / You / We / They He / She / It
   肯定句（Positive）    动词原形（V） 动词第三人称单数形式（V+S）
   否定句(Negative)   don’t + 动词 doesn’t + 动词原形
一般疑问句(Yes/No) Do… ? Yes, I do. Does…(动词原形)…? No ,she doesn’t.
特殊疑问句(wh-) What do …? How does she…(动词原形)…?
(3) 动词第三人称单数形式
a. Most verbs                 +s    walk-walks
b. Verbs ending in a consonant +y    -y +ies fly-flies
c. Verbs ending in s, sh, ch or x    +es watch-watches
d. Others do-does ,have-has, go-goes

2．现在进行时,
（1）表示正在发生的动作，通常用“now, look”.
（2）基本形式： be + 动词+ing
    eg: I am(not) doing my homework.
You/We/They   are(not)   reading.
He/She/It   is(not) eating.
What are you doing?
Is he reading?
（3）动词的现在分词形式（do+ing）
Most verbs   +ing   walk—walking
Verbs ending in e -e + ing come—coming
Short verbs ending in a vowel + a consonant Double
consonant run-running
swim-swimming

3. 一般过去时态
（1） 表示过去已经发生的事情,通常用 “last week, just now, yesterday”等词。
（2） be 动词的过去式: am/is—was     are—were
I/He/she/it was(not)….   You/we/they were….
一般疑问句was, were 放在句首。
   （3）过去式基本结构
   肯定句（Positive） 动词过去式 I went shopping last night.
   否定句(Negative) Didn’t + 动词原形 I didn’t go shopping last night.
一般疑问句(Yes/No) Did …+ 动词原形…? Did you go shopping last night?
特殊疑问句(wh-) What did…+ 动词原形…? What did you do last night?
(4)动词过去式的变化：
规则动词的变化：
一般动词     +ed planted, watered, climbed
以不发音的e结尾                    +d liked
辅音字母加y结尾 -y+ ied study—studied, cry- cried
重读闭音节单词，末尾只有一个辅音字母 双写最后一个字母+ed stop –stopped
plan - planned
不规则动词的变化：
原形 过去式 原形 过去式 原形 过去式 原形 过去式
sweep swept   teach taught    have had       go went
keep kept     think thought   do did         find found
sleep slept   buy bought      eat ate        say said
feel felt     drink drank     is/am was      take took
read read     give gave       are were       mean meant
put put       sing sang       drive drove    meet met
cut cut       begin began     speak spoke    make made
let let       ring rang       write wrote    see saw
fly flew      run ran         ride rode      come came
draw drew     sit sat         hear heard     tell told
grow grew    learn learned/ learnt    get got    know knew

4．一般将来时
一般将来时表示将来打算做的事或将要发生的事情。
结构：be going to +动词原形
例如：I’m going to visit my grandpa next week.

与这个时态连用的时间状语常用：
tonight, tomorrow, the day after tomorrow, next week, in three hours, two days later 等。
一般将来时态与其它结构表将来情况的区别：
一般将来时态 ：主要从时间的角度表将要发生的动作或情况。

一般将来时除了使用“shall／will + V…”以外，也可以使用下列的句式来表达。

1．be going to + V … （即将会……；打算将……）

be going to 结构 ：①表（主观上）打算或准备做某事时。 ②表有发生某事的预兆时。
e.g. They are going to have a competition with us in studies. It is going to rain.
据以上区别，故下面一句是错的：
I am going to be eighteen years old next year.
应改为： I shall be eighteen years old next year.
be about to do sth 结构 ：意为“刚要做某事”、“马上要做某事”强调时间之紧迫性。
e.g. We are about to discuss this problem.
我们将马上讨论这个问题。
be to do sth 结构： 表示按计划、安排、规定将实施某事或表示注定会发生某事。
e.g. When is the train to leave.