(一) 一般现在时：
1.用法：反复性或经常性发生的动作或存在的状态；表示客观真理；
2.时间状语：(1) every +单数时间名词（day/ month /year /week等）；
(2) 频率副词：usually/ often/ sometimes/ always等。
3.谓语动词形式：
(1)be动词：am / is / are
(2)实义动词：原形和第三人称单数形式（简称三单形式）；
(3)动词三单形式的转换规则：
①一般情况下，直接加“s”；
e.g.help—helps
like—likes
come—comes
play—plays
find—finds
②以s, x, sh, ch, o结尾的动词，加“es”；
e.g. guess—guesses
fix—fixes
teach—teaches
finish—finishes
go—goes
do—does
③以辅音字母加“y”结尾的动词，变“y”为“i”，再加“es”。
e.g. study—studies
worry—worries
try—tries
carry—carries
e.g. Tom goes to school every day.
They often stay at home on weekends.
Mary and I are friends now.
(二)现在进行时：
1.用法：表示说话时某个动作正在发生或进行；也可表示近期存在的状态；
2.时间状语：now(现在) ;
at present(目前);
at the moment(此时此刻);
look; listen等；
3.谓语动词形式：be动词（am/ is/ are）+ doing(动词的现在分词形式);
4.动词-ing形式的变化过则：
①一般情况下，直接加-ing;
e.g.go----going
ask ----asking
look----looking
carry—carrying
②以不发音的e结尾的动词，去e加-ing;
e.g.write----writing
make----making
take----taking
move—moving
live—living
leave—leaving
③以重读闭个辅音音节结尾的动词，末尾只有一个辅音字母，双写这个辅音字母，再加-ing；
e.g.get----getting
sit----sitting
put----putting
run----running
begin----beginning
plan—planning
cut—cutting
get—getting
beg—begging
④注意（特殊）：die----dying
lie----lying
tie----tying
picnic----picnicking
panic----panicking
e.g. Listen, they are singing in the next classroom.
Tom and Mary are having an English class at the moment.
(三)一般过去时：
1. 用法：表示过去发生的动作或存在的状态；
2. 时间状语：(1)last（上一个） +表示时间的单数可数名词(day/month/ week /year等)；
(2)时间段+ ago(以前)：e.g. three days ago三天以前；
(3) in +过去的年份：e.g. in 1998
(4)in the past在过去；
(5)then = at that moment在那时
3.谓语动词形式：
(1)be动词: was(am/is的过去时);
were(are的过去时)；
(2)实义动词：过去式形式：
(3)动词过去式（过去分词）的转化规则
规则动词的转化规则：
①一般情况下直接加ed；
e.g.look----looked
play----played
start----started
②以e结尾的动词加d；
e.g.live----lived
hope----hoped
use----used
face----faced
③以重读闭音节结尾的，末尾只有一个辅音字母的，双写这个辅音字母，再加ed；
e.g.stop----stopped
plan----planned
permit----permitted
beg----begged
④以辅音字母加y结尾的动词，变y为i再加ed；
e.g.study----studied
carry----carried
worry----worried
不规则动词的变化规则（特殊记忆，见课本后）
①原形，过去式和过去分词形式相同：
e.g. hit----hit----hit
set----set----set
put----put----put
cut----cut----cut
cast----cast----cast
cost----cost----cost
shut----shut----shut
hurt----hurt----hurt
burst----burst----burst
spread----spread----spread
② 过去式和过去分词同形：
e.g. feed----fed----fed
bleed----bled----bled
bend----bent----bent
buy----bought----bought
breed----bred----bred
fight----fought----fought
bring----brought----brought
catch----caught----caught
sell----sold----sold
leave----left----left
meet----met----met
send----sent----sent
find----found----found
sleep----slept----slept
teach---taught----taught
think----thought----thought
③原形，过去式和过去分词均不相同：
e.g. lie----lay----lain
see----saw----seen
rise----rose----risen
give----gave----given
begin----began----begun
blow----blew----blown
know----knew----known
grow----grew----grown
break----broke-----broken
drink----drank----drunk
speak----spoke----spoken
swim----swam----swum
e.g. Tom went to school yesterday.
We are classmates three years ago.
Everything went well at that moment.
(四)过去进行时:
1.用法：过去某个时刻正在进行或发生的动作或存在的状态；
2.时间状语：then;
at that moment;
at three yesterday等
3.谓语动词形式：be动词（was/ were）+ doing;
e.g.They are building the house on that day in 1997.
Tom and Mary are chatting when I came yesterday.
