内容正文:
八年级英语下册
重要知识点和语法
一、动词不定式(to do)
【核心用法】
1.表目的:用来表示动作的目的,可译为“为了……”
[例句]I listen to music to relax after class.(我课后听音乐来放松。)
[例句]She exercises every day to keep healthy.(她每天锻炼为了保持健康。)
2.作宾语补足语:跟在动词后,补充说明宾语的动作
[常用动词]want/ask/tell/advise/encourage/order sb.to do sth.
[例句]My teacher told me to finish homework on time.(老师告诉我按时完成作业。)
[否定式]ask sb.not to do sth.(要求某人不要做某事)
3.作宾语:跟在某些动词后作宾语
[常用动词:want/hope/decide/plan/try/learn to do sth.
[例句]I decided to join the reading club.(我决定加入读书俱乐部。)
4.易混搭配区分
stop doing sth.:停止正在做的事(Stop talking! 别说话了!)
stop to do sth.:停下来去做另一件事(Stop to have a rest.停下来休息一下。)
enjoy/practice/finish/mind/keep doing sth.(这些动词后只能加doing)
二、情态动词should/could表建议
【核心用法】
1.should(应该):用于提出劝告、建议,语气较直接,适用于所有人称
[结构]主语 + should + 动词原形 / shouldn't + 动词原形
[例句]You should go to bed early.(你应该早点睡觉。)
[例句]You shouldn't eat too much junk food.(你不应该吃太多垃圾食品。)
2.could(可以):用于提出委婉的建议,语气更柔和
[结构]You could + 动词原形
[例句]You could ask the teacher for help.(你可以向老师求助。)
3.反身代词用法(配套考点)
[构成]myself/yourself/himself/herself/itself/ourselves/yourselves/themselves
[用法]表示“某人自己”,常与by/for/enjoy/help oneself搭配
[例句]He can look after himself.(他能照顾自己。)
[例句]Help yourselves to some fruit, kids.(孩子们,随便吃点水果。)
三、状语从句(until/so that/although/if)
1.until引导的时间状语从句
[用法]表示“直到……才”,主句动作持续到从句动作发生
肯定句:主句用延续性动词→ I waited until he came back.(我一直等到他回来。)
否定句:not...until → 主句用短暂性动词 → I didn't leave until he came back.(直到他回来我才离开。)
2.so that引导的目的状语从句
[用法]表示“为了……,以便……”,从句常加can/could/will/would
[例句]He studies hard so that he can pass the exam.(他努力学习为了能通过考试。)
3.although引导的让步状语从句
[用法]表示“虽然……但是……”,[注意]although不能与but连用
[例句]Although he is tired, he still keeps working.(虽然他很累,但他仍然坚持工作。)
4.if引导的条件状语从句
[用法]表示“如果……”,遵循“主将从现”原则(主句将来时,从句一般现在时)
[例句]If it rains tomorrow, we will not go hiking.(如果明天下雨,我们就不去远足。)
四、形容词/副词的比较级和最高级
1.构成规则
变化类型
规则
例词
一般情况
比较级+er,最高级+est
small→smaller→smallest
以不发音e结尾
比较级+r,最高级+st
nice→nicer→nicest
重读闭音节(辅+元+辅)
双写尾字母+er/est
big→bigger→biggest
辅音字母+y结尾
变y为i+er/est
easy→easier→easiest
多音节/部分双音节
比较级+more,最高级+most
beautiful→more beautiful→most beautiful
不规则变化
单独记忆
good/well→better→best;bad/ill→worse→worst;many/much→more→most;far→farther/further→farthest/furthest
2.核心用法
比较级用法表示“两者之间比较”
结构1:A + be + 比较级 + than + B → Tom is taller than Kate.(汤姆比凯特高。)
结构2:A + 实义动词 + 比较级 + than + B → I jump farther than him.(我跳得比他远。)
倍数表达:A is 3 times bigger than B.(A比B大三倍。)
最高级[用法]表示“三者及以上中最……”
结构1:A + be + the + 最高级 + of/in...→ He is the tallest in his class.(他是班里最高的。)
结构2:A + 实义动词 + (the) + 最高级 + of/in...→ I jump (the) farthest in my class.(我是班里跳得最远的。)
[注意]形容词最高级前必须加the,副词最高级前the可省略
五、过去进行时(was/were + doing)
【核心用法】
1.结构主语 + was/were + 现在分词(doing)
肯定句:I was reading at 8 last night.(昨晚8点我正在看书。)
否定句:I wasn't reading at 8 last night.
一般疑问句:Were you reading at 8 last night? Yes, I was./No, I wasn't.
2.[用法]表示过去某一时刻/某一段时间内正在进行的动作
标志词:at 8 last night, this time yesterday, from 7 to 9 yesterday
3.when/while的区别(高频考点)
when:后可接短暂性动词(一般过去时)或延续性动词(过去进行时)
[例句]When he came in, I was reading.(当他进来时,我正在看书。)
while:后只能接延续性动词(过去进行时),强调两个动作同时进行
[例句]While I was reading, he was listening to music.(我看书时,他在听音乐。)
六、状语从句(so…that/unless/as soon as)
1.so…that…引导的结果状语从句
[用法]表示“如此……以至于……”
[结构]so + 形容词/副词 + that + 从句
[例句]He was so tired that he fell asleep immediately.(他太累了,立刻就睡着了。)
2.unless引导的条件状语从句
[用法]表示“除非……,如果不……”,相当于if...not
[例句]Unless you work hard, you will fail the exam.(除非你努力学习,否则你会考试不及格。)
[注意]遵循“主将从现”原则
3.as soon as引导的时间状语从句
[用法]表示“一……就……”
[例句]I will call you as soon as I arrive in Beijing.(我一到北京就给你打电话。)
[注意]遵循“主将从现”原则
七、现在完成时(have/has + 过去分词)
1.[结构]主语 + have/has + 动词过去分词(done)
肯定句:I have finished my homework.(我已经完成作业了。)
否定句:I haven't finished my homework.
一般疑问句:Have you finished your homework? Yes, I have./No, I haven't.
2.两大核心用法
用法1:过去动作对现在造成的影响/结果
标志词:already(肯定)、yet(否定/疑问)、ever、never、just
[例句]I have already seen this movie.(我已经看过这部电影了。)
用法2:过去动作持续到现在
标志词:for + 时间段、since + 时间点/从句
[例句]I have lived here for 5 years.(我在这里住了5年了。)
[例句]I have lived here since 2021.(我从2021年就住在这里了。)
3.易错点
短暂性动词(buy/leave/join等)不能与for/since连用,需转换为延续性动词
例:buy → have;leave → be away;join → be in
错误:I have bought this car for 3 years.
正确:I have had this car for 3 years.
八、句子成分与基本句型
【句子成分】
1.主语:句子陈述的对象(名词/代词/动名词等)→ He plays basketball.
2.谓语:主语发出的动作(动词)→ He plays basketball.
3.宾语:动作的承受者(名词/代词等)→ He plays basketball.
4.系动词:表示状态/变化,无实际动作(be动词、感官动词look/sound/smell/taste/feel、keep/become等)→ The food tastes delicious.
5.表语:系动词后的成分(形容词/名词/介词短语等)→ The food tastes delicious.
6.定语:修饰名词/代词(形容词/名词/介词短语等)→ This is a red apple.
7.状语:修饰动词/形容词/副词/句子(时间/地点/方式/原因/条件等)→ He runs fast.
8.补语:补充说明主语/宾语(宾语补足语最常见)→ You should keep the room clean and tidy.
【基本句型】
1.主语 + 谓语(不及物动词)→ He runs.
2.主语 + 谓语(及物动词)+ 宾语 → He plays basketball.
3.主语 + 系动词 + 表语 → He is happy.
4.主语 + 谓语 + 间接宾语 + 直接宾语 → He gave me a book.
5.主语 + 谓语 + 宾语 + 宾语补足语 → He made me happy.
九、易混语法点(高频考点)
易混点
区别
例句
few/a few/little/a little
few/a few修饰可数名词;little/a little修饰不可数名词<br>few/little表否定(几乎没有);a few/a little表肯定(有一点)
I have a few friends.(我有几个朋友)<br>I have little time.(我几乎没时间)
too/either/also
also用于句中;too用于肯定句句末;either用于否定句句末
I also like it./ I like it too./ I don't like it either.
in/on/at(时间介词)
in+年/月/季节/上午/下午;on+具体某一天;at+具体时刻
in 2026 / on May 1st / at 7 o'clock
borrow/lend/keep
borrow(借入,borrow...from...);lend(借出,lend...to...);keep(保留,延续性动词)
I borrow a book from him./ He lends a book to me./ I keep the book for 3 days.
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