一、重点语法解析Past nowYesterday , we Now , the classroomcleaned the classroom. is clean becausewe have cleaned it.1. My father bought many books for me yesterday .Now , I have a lot to read because________________________________2. I saw this film last week.Now, I know this film because I_____________________.3. I did my homework yesterday.Now, I can give it to the teacher because I______________Past nowI began to teach I have taught English at this English at this school five school for five years.years ago.1. I am a doctor. I began to work when I was 22.Now , I am 26. I________ for four years.2. We went to the USA last Monday. Today is Monday . We _________(stay) in the USA since last Monday.1、现在完成时：表示过去发生或已经完成的某一动作对现在造成的影响或结果，或从过去开始一直延续到现在的动作或保存的状态，强调的是现在的情况，常用for和since表示一段时间的状语或so far，now，today，this week (month，year)等表示包括现在时间在内的状语。
不能和表示过去的时间状语连用（如：in 1990，last Sunday 等）。
例如：He has studied English for 5 years.He has studied English since 2001.Now I have finished the work.注意：表过去某一时间发生的动作或状态一直延续到现在（强调现在），动作或状态一般是延续性的，因此要用表延续性的动词或表状态的动词。
表示短暂时间动作的词，如:come，go，die，marry，buy等的完成时不能与for，since等表示一段时间的词连用。
也不能用于how long引导的疑问句中。
如不能说：He has borrowed the book for two months.(ⅹ)但可以说：He has kept the book for 2 months.或：It has been 2 months since he borrowed the book.或：Two months has passed since he borrowed the book.这些瞬间动词常与它对应的可以表示时间段的词语进行互换。
become—be borrow—keep buy—havebegin (start)—be on open—be open die—be deadleave--be away come--be here/in go out—be outjoin--be a member/be in begin to study--study注明：非延续性动词在否定结构中可用于现在完成时态：I haven’t bo ught anything for two days.2、现在完成时的结构：have / has + 过去分词否定结构：haven’t / hasn’t + 过去分词一般疑问句中：Have/Has+主语+动词的过去分词3、一般过去时：一般过去时只表示过去的动作或状态，和现在不发生关系（即动作或状态在现在已经结束），它可以和表示过去的时间状语连用。
现在完成时与一般过去时的区别：现在完成时用来表示之前已发生或完成的动作或状态，其结果的确和现在有联系。
动作或状态发生在过去，但它的影响现在还存在；而一般过去时表示过去的事实，不表示和现在的关系。
I have just been to London. I went there last month. 我刚去过伦敦，是上个月去的。
1. 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。
2. 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: yesterday, last week，…ago, in1980, in October, just now, 具体的时间状语共同的时间状语:this morning, tonight, this April, now, once，before, already, recently，lately现在完成时的时间状语for, since, so far, ever, never, just, yet, till / until, up to now, in past years, always,3.现在完成时可表示持续到现在的动作或状态，动词一般是延续性的，如live, teach, learn, work, study, know.过去时常用的非持续性动词有come, go, leave, start, die, finish, become, get married等。
举例：I saw this film yesterday. （强调看的动作发生过了。
）I have seen this film.（强调对现在的影响，电影的内容已经知道了。
）Why did you get up so early? （强调起床的动作已发生过了。
）Who hasn't handed in his paper? （强调有卷子，可能为不公平竞争。
）She has returned from Paris. 她已从巴黎回来了。
She returned yesterday.她是昨天回来了。
He has been in the League for three years. (在团内的状态可延续)He has been a League member for three years. (是团员的状态可持续)He joined the League three years ago. ( 三年前入团，joined为短暂行为。
)I have finished my homework now.---Will somebody go and get Dr. White?---He's already been sent for.句子中如有过去时的时间副词（如yesterday, last, week, in 1960）时，不能使用现在完成时，要用过去时。
（错）Tom has written a letter to his parents last night.（对）Tom wrote a letter to his parents last night.二、动词的过去分词的规则变化2、不规则动词的过去式以及过去分词巧记规律：AAA：cost-cost-cost read-read-readput-put-put cut-cut-cutlet-let-let set-set-setbeat-beat-beat hit-hit-hit hurt-hurt-hurt spit-spit-spit rid-rid-rid注：原形、过去式和过去分词的词形和读音都相同的单词，结尾字母一般是t或d。
特殊：动词read的过去式和过去分词虽然词形与原形一致，read-read-read，但发音分别是[ri:d]-[red]-[red]。
ABA（含规则动词）：有些动词的过去分词与原形是一样的:run-ran-run come-came-comebecome-became-become overcome-overcame-overcome ABB（含规则动词）：1.另有一些其它形式的变化。
have (has)-had-had leave-left-leftlose-lost-lost make-made-madefeel-felt-felt spell-spelt-spelt stand-stood-stood2. 改变单词中间元音字母。
sit-sat-sat (babysit) win-won-wonshine-shone-shone hold-held-heldfind-found-found hear-heard-heardhang-hung (hanged)-hung (hanged)ABC：有些动词的过去分词是在原形词尾加n或en，变成以en结尾的单词。
take-took-taken give-gave-givenfall-fell-fallen eat-ate-eatenwrite-wrote-written speak-spoke-spokenfreeze-froze-frozen ride-rode-riddenget-got-gotten (got) forget-forgot-forgotten (forgot)特殊：am/is-was-been are-were-been,do (does)-did-done go-went-gonesee-saw-seen show-showed-shown (showed)lie-lay (lied)-lain (lied)三、重难点词汇精讲1.Have you ever been to an amusement park?have been to ...have been to + 地点：去过某地（已回）have been to表示“到(去)过某处”，现在已不在那个地方。
如：He has been to England．他曾到过英国。
(现在已经不在英国了) Have you ever been to the Great Wall？你到过长城吗?（现在已经不在长城上）have gone to + 地点：去了某地（未回）have gone to表示“去了某处”，“到某处去了”，现在已不在说话的地点了。