现在完成时的几个问题

Question

现在完成时的语法是规定在句末加上时间短语时：for+时间段，since+时间点
那时间段和时间点的区别是什么呢？
最好是文字说明再加例句说明

Answer 1

since
表示从什么时候开始
例子 since 2004
是指 2004到现在

for
是指一段时间
例子 for 2004 to 2006
指的是04年到06年

SINCE后面加时间点
例如 SINCE 1990 意思就是从1990开始
1990就是一个时间点；

而FOR后面是加时间段
例如 FOR 5 YEARS
意思就是5年的时间

since+过去某一时间或句子,for+一段时间
She has taught in the school for ten years. 她在这所学校教书已经10年了。
I haven't eaten anything since breakfast. 我从早饭起就一直没有吃东西。

Answer 2

since是自从什么时候开始到现在为止！
后接一个时间点。
I have kept this book since 4 weeks ago

for是一个时间段！
后接一段时间
I have kept this book for 4 weeks
注（超重要）：瞬间动词（buy,die,join,lose……）不能直接与for since 连用。要改变动词
come-be
go out-be out
finish-be over
open-be open
die-be dead
………………
1.have代替buy
My brother has had(不能用has bought) this bike for almost four years.
2、用keep或have代替borrow
I have kept(不能用have borrowed) the book for quite a few days.
3、用be替代become
How long has your sister been a teacher?
4、用have a cold代替catch a cold
Tom has had a cold since the day before yesterday.
5、用wear代替put on
b)用“be＋形容词”代终止性动词
1、be＋married代marry 2、be＋ill代fall (get) ill
3、be＋dead代die 4、be＋asleep代fall (get) asleep
5、be＋awake代wake/wake up 6、be＋gone代lose,die,sell,leave
7、be＋open代open 8、be closed代close/shut
9、be＋missing(gone,lost)代lose
c)用“be＋副词”代终止性动词
1“be＋on”代start,begin
2“be＋up”代get up
3“be＋back(to)”代return to,come back to,go back to
4“be here (there)”代come(arrive,reach,get) here或go (arrive,reach,get) there等等
d)用“be＋介词短语”代终止性动词
1.“be in/at +地点”代替go to /come to
2.用be in the army 代替join the army
3.“be in/at +地点”代替move to
常用瞬间动词变延续性动词表：
1. have arrived at/in sw. got to/reached sw. come/gone/moved to sw.
→have been in sw./at…相应的介词
2. have come/gone back/returned → have been back
3. have come/gone out →have been out
4. have become → have been
5. have closed / opened→ have been close/open
6. have got up → have been up；
7. have died → have been dead；
8. have left sw. → have been away from sw.
9. have fallen asleep/got to sleep → have been asleep；
10. have finished/ended/completed → have been over；
11. havemarried → have been married；
12. have started/begun to do sth. → have done sth. ；
13. have begun → have been on
14. have borrowed/bought →have kept/had
15. have lost → haven’t had
16. have put on →have worn
17. have caught /get a cold → have had a cold；
18. have got to know → have known
19. have/has gone to → have been in
20. have joined/have taken part in the league/the Party/the army
→have been a member of/ have been in/have been the Party’s member/the league member/the soldier…

Answer 3

for+时间段谓语动词要是延续性动词
since+时间点谓语动词是非延续性动词