8年级上册U5-U6现在完成时知识要点.doc

现在完成时必须掌握和熟记的知识要点1 基本结构：have / has（主语是三单时） + 过去分词（规则动词+ed，不规则动词记课本P141- P142表）2 现在完成时常用的副词 用于句中的：ever（曾经）, never（从不）, already（已经）, just（刚刚） 用于句末的：yet（尚未，已经）, already（已经）, before （以前） 用于肯定句：already（已经） 用于疑问句：yet（已经）, ever（曾经） 用于否定句：yet（尚未，还没有）, never（从不，从来没有） 例如：1） Have you ever been to Hongkong ? No, I have never been there. 2） Have you finished your homework yet ? No, not yet. / No, I havent yet. 3） He has already read the book. 也可以说成：He has read the book already. 3 与现在完成时有关的几个必须理解区分的短语： have / has gone to + 地点 表示：去了某地，人还没回来 have / has been to + 地点 表示：去过某地，人已经回来，常与ever, never, times（次数）连用 have / has been in + 地点 表示： 去了某地并在当地停留一段时间，常与for, 或since 连用例如：1）A: Where is your father ? B: He has gone to Beijing. He will be back next week. (人还没回来) 2）A：Hi, John. Long time no see. Where have you been ? B: I have been to Hongkong. Ive been there twice this month. （人已回来） 3）Alice has been in Shanghai for a week. She will be back tomorrow. （人还在上海）4 关于for, since 的用法：for + 时间段， 表示“有（多长）一段时间了”， 如：for five years, for a few dayssince的用法比较复杂，要记住以下4点：1） since + 过去一个时间点，表示“自从以来”，如：since 1990, since last week2） since + 时间段 + ago, 相当于：for + 时间段如：She has stayed in Guangzhou since three months ago = She has stayed in Guangzhou for three months.3) 主句（现在完成时）+ since + 从句（一般过去时） 如：Mr. Wang has worked here since he came to the city.4) It + is + 时间段 + since + 从句（一般过去时） 如：It is three years since I began to learn English. 我学英语已有3年了。 = I have learned English for three years.5 一般过去时与现在完成时的用法区别：1) 看特征词：一般过去时常用的时间状语是：yesterday, last , ago, in +年份， 记住这些词都不能跟现在完成时连用。如：I played football yesterday. 不可以说：I have played football yesterday.（一般过去时） （现在完成时）现在完成时常用的时间状语是：already, yet, ever, never, for . , since , 另外用于现在时的时间状语也可以用于现在完成时，如：He has already eaten breakfast now. 2) 关于特殊疑问句when 和how long When一般用于一般过去时，问这件事是过去什么时候做的， How long 一般用于现在完成时，问这件事做了多长时间，如：A: I have finished writing the reportl.B: When did you write it ?A: I wrote it last night.A: I have finished writing the report.B: How long have you written it ?A: I have written it for three hours.3) 假如没有任何特征词，可通过上下文判断时态，一般现在是表示“过去某一时间做了什么”，跟现在无关； 现在完成时表示“现在已经做过什么”，对现