一般过去时&现在完成时
1. 现在完成时的构成：谓语动词用have/has+动词的过去分词(done)
2. 现在完成时的用法：
①表示过去发生的动作对现在的影响；
②表示过去发生的动作持续到现在。
3. 时间状语：通常和already（用于肯定句），yet（用于否定句和疑问句中），since（自从），for+一段时间，recently, ever, never, by now, so far, in the past few years, in the last ten weeks等连用。
☆have been to/have gong to的区别join的四种用法
have been to
have gone to
曾经去过某地（已回）
去某地了，现在还在那个地方或去那的路上
________________________他去过美国。（他现在不在美国）
________________________他去美国了。（他已经在美国了或者去美国的路上）
☆现在完成时常与次数连用：
______________________________（我去过澳大利亚两次）
☆瞬间动词与持续性动词
瞬间动词表示短暂的、不能持续一段时间的动作，如：begin, start, finish, become, arrive等。
持续性动词表示持续一段时间的动作，如：have, keep, wait, work, learn, live等
注意：持续性动词可以和“for+时间段”、“since+某一时间”连用；但瞬间动词不能与“for+时间段”、“since+某一时间”连用。例如：
I have bought the bike for six months. （×）
I have had the bike for six months. （√）
She has borrowed the book for two weeks. （×）
She has kept the book for two weeks. （√）
He has joined the party since ten years ago. （×）
He has been in the party since ten years ago. （√）
They have gone to Beijing since two months ago. （×）
They have been in Beijing since two months ago.（√）
瞬间动词与延续性动词之间的转化：
leave ---_______
borrow --_______
buy ---_______
begin/start --- be on
die ---_______
finish/end --- be over
join --- be in+组织机构
get up---be up
fall ill ---  be ill
open sth --- keep sth open
come here --- be here
become --- be
catch a cold ---_______
come back --_______
go (get) out —be out
get to/ arrive/reach --- be (in)
put on --- wear
leave ---_______________
比较一般过去时与现在完成时
a)一般过去时表示过去某时发生的动作或单纯叙述过去的事情，强调动作；现在完成时为过去发生的，强调过去的事情对现在的影响，强调的是影响。
b)一般过去时常与具体的时间状语连用，而现在完成时通常与模糊的时间状语连用，或无时间状语。
一般过去时的时间状语：_________________________________________等，皆为具体的时间状语。
现在完成时的时间状语：_____________________________________________________等，皆是不确定的时间状语。
现在完成时表示持续到现在的动作或状态时，动词一般是延续性的，如____________________________________________,而不会用到非持续性动词如_______________________________________________等。
Ex1:判断正误：
1．I played tennis yesterday.  (  )
  I have played tennis yesterday.  (  )
2．I had lunch just now.  (  )
  I have just had lunch.  (  )
3．When did you come here?  (  )
  When have you come here?  (  )
4．I’ve been busy since yesterday.  (  )
  I’ve been busy yesterday.  (  )
【答案】1. T F; 2. TT; 3. T F; 4. T F
用于现在完成时的句型
●It is the first / hat…结构中的从句部分，用现在完成时。例如：
It is the first time that I have visited the city. 这是我第一次访问这城市。
This is the first time (that) I've heard him sing.　这是我第一次听他唱歌。
注意：It was the third time that the boy had been late.
●This is +形容词最高级+that…结构，that 从句要用现在完成时。例如：
This is the best film that I've (ever) seen. 这是我看过的最好的电影。 
【例1】-Do you know our English teacher at all? 
        -No, this is the first time I ______ her.
A. saw                B. have seen                C. was seeing                D. am seeing
【答案】B
【解析】This is the first time 后面所加从句应为现在完成时，故选 B。
【例2】 -Have you ______ been to our town before?
    -No, it's the first time I ______ here.
A. even, come      B. even, have come        C. ever, come                D. ever, have come
【答案】D
【解析】ever 意为曾经或无论何时，反意词为 never，此两词常用于完成时。
since的四种用法
a)since +过去一个时间点（如具体的年、月、日期、钟点、1980, last month, half past six）。例如：
___________________________________ 1989起，我一直在这儿。
b)since +一段时间+ ago。例如：
_____________________________________ 我在这儿，已经有五个月了。
c)since +从句。例如：
_____________________________________ 你走后，变化可大了。
Great changes have taken place since we were here. 我们走后，变化可大了。
d)It is +一段时间+ since从句。例如：
_____________________________________ 我考上研究生有两年了。
【例1】—I'm sorry to keep you waiting.
        —Oh, not at all. I ______ here only a few minutes.
A. have been                B. had been          C. was            D. will be
【答案】A
【解析】等待的动作由过去开始，持续到现在，应用现在完成时。

Practice
I. 用for, since, /, in填空
1.I moved here __________ two years ago.
2.He has learned playing the piano __________ two years ago.
3.Peter has written 15 articles__________ last month.
4.Tom became a member in the football club __________ 1999.
5.We went to the Shanghai Museum __________ yesterday.
6.It has been five years __________ she left here.
7.He has lived in Nanjing __________ the year before last.
8.I've known him __________ we were children.
9.Our teacher has studied Japanese __________ three years.
10.She has been away from the city __________ about ten years.
【答案】1. /; 2. since; 3. since; 4. in; 5. /; 6. since; 7. since; 8. since; 9. for; 10. for;
II. Choose the best answer. （选择最恰当的答案）
1. The Oriental Pearl TV Tower ______ tens of thousands of visitors since 1995.
A. attracted        B. attracts        C. has attracted        D. will attract