八年级英语上册第三单元Section A知识点归纳：
1.形容词、副词的比较级的相关知识：
（1）。规则变化：以e结尾的家r，例如：late---later, 以重读闭音节且一个辅音字母结尾的双写这个辅音字母再加er ，例如：big—bigger, thin----thinner, fat---fatter,(闭音节是指音节中的元音字母发单元音短音) ，以辅音字母家y结尾的双音节词，（每个音节之间有很短暂的停顿），把y变i再加er,以ed和ing结尾的形容词在词前加more，例如：tired---more tired , exciting----more exciting, 以ly结尾的副词在词前加more,例如：loudly----more loudly, quietly----more quietly (注意：friendly和lovely 为形容词) 多音节词在词前加more ,例如：popular---more popular
（2）.常见不规则变化：good/ well----better , bad/ badly----worse , little----less, far---farther(主要指距离远)，或further(主要指程度深) old—elder (年长的例：my elder brother 我的哥哥)
（3）.形容词和副词的前后比较对象要一致（即后面的比较对象要和前面的主语保持一致）例如：Tom has longer hair than his brother .(本句中Tom为主语，所以than 后应该加的是his brother ，而不是his brother’s hair) Tom’s hair is longer than his brother’s .(本句中主语是Tom’s hair, 所以比较的对象应该是his brother’s hair )
(4)双方比较表示一方不如另一方时用not as/ so ……as 或者less than 例如：This room is more beautiful than that one .=That room is not as/ so beautiful as this one .= That room is less beautiful than this one.
(5) 表示一方随另一方的程度而变化用the +比较级，the+比较级，越……..,越……….例如：The more, the better 越多越好（多多益善）The harder he works, the happier he feels. 及时练习：The more he eats, the _________( fat) he gets. (6)不与其他事物比较，表示本身程度的变化时，用比较级+and+比较级结构。例如：The weather is getting hotter and hotter.天气正变得越来越热。The girl becomes more and more beautiful .
(7) 通常可以用在比较级前面的词有much, a little, a bit , a lot, even,或名词短语。例如：Tom is a little than me ,but I am much heavier than him. 例2：I am twenty,my brother is eighteen ,so I am two years old than my brother .
(8)特殊疑问句中的两者选择，例如：Which is more outgoing, Tom or Jim?
(9) 句尾或句首有of the two……，表示“两者中较……..的一个”限制时比较级前需加上the ,例如：Mary is the taller of the two girls.(注意：此为比较级前使用the 的唯一情况)
（10）形容词、副词比较级句子构成，一者：Tom works hard. ------两者：Tom works harder than Jim .(用than 连接比较对象，同时将原句中的形容词或副词变为比较级)
11.比较级及时练习题：练习：
（2）1. old ______ _ 2. busy _________ 3. thin ________ 4. many _________ 5. slow ________ 6. delicious _________ 7. bright __________ 8. lazy________ 9. safe ________ 10. bad__________ 11. well_________ 12. sad _________
（2）用所给词的适当形式填空：
1. Bob is ________ ( young ) than Fred ，but __________ (tall) than Fred.
2. Yingtian is not as ___________ (tall) asYongxian.
3. Almost all the students' faces are the same but Li Deming looks _______ (fat) than before .
4. Which is _________ (heavy), a hen or a chicken?
5. A dictionary is much _________ (expensive) than a story-book.
6. An orange ia a little ______ (big) than an apple, but much ________ (small) than a watermelon.
7.Miss Chen is __________ _________than Mr. Wang. (popular)
8. Mr. Lin is________ ________ _________ Mr. Brown. (sad)
9. Question A is _______ ________ _________ ________ Question B. (important)
10. A rose is________ ________ __________ ________ a weed(野草). (beautiful)
11. He is ________than any other boy in the class.（clever）
12. Tom drives much ________ ________than John. (careful)
2.as…….as 的用法
(1)as….as….中间接形容词或副词的原级，第一个as为副词，第二个as为介词。当谓语动词是连系动词时，中间加形容词；当谓语动词为副词时，中间接副词。例如：Tom is a s tall as me. And he studies as hard as me ,too.如果第二个as后用主格形式，则需要加动词。例如：Tom is as tall as I am. And he studies as hard as I do.(用do代替前面的动词，如果是三单用does,过去式用did)。
(2)as….as…在否定句中可用so ….as 替换。意思是前者不如后者。例如：H e is not as/so tall as me.=I am taller than him.
(3)as….as…..中间如果涉及数量或程度时可用much+不可数名词或many+可数名词，例如：He has as many books as his brother. Jane got as much money as his sister.
(4)中间加形容词时，还可以加名词，顺序是as+形容词+a/ an+单数名词+as .例如：She is as good a teacher as her mother. 她和她妈妈一样是位好老师。
拓展词组：as soon as……，一…..就………as long as……，只要…….
3对应反义词：tall----short, thin----heavy/ fat ,quietly----loudly, long---short,
4 .both 的用法both指两者都（1）both与名词代词连用，顺序是both of+the+名词或代词，例如：Both of the cats are lovely. Both也可直接加名词，例如：Both cats are lovely.
(2)both与代词直接连用时不能说both+代词，例如both we,both us 都是错误的，要加上of 即both of us 例如：Both of us like sports.
(3)both 与动词连用时放在be动词、助动词、情态动词之后，行为动词之前，例
