Unit 4 Our World
Topic 1 Plants and animals are important to us.pitbull新歌
一、语言知识点
（1）单词：
sky, clear, nature, discuss, thin, cow, sheep, goo, rabbit, above, joy, ro, snake, fox, feed, cover, surface, dark, forest, control, wood, rubber, protect, fact, large, lake, a, ocean, drop, land, whale, kill, south, bear, wolf, feed on, in fact, make up, every drop of water
（2）句子：
aaa软件教育 1．The hens are much smaller than the cows.
2．The mice are the smallest of them.
3．I think animals are more interesting.
4．We share the world with them.
5．Incts feed on plants.
japane teacher free 6．If there are no plants or incts…, what will our world be like?
7．Rainforests cover 6% of the earth's surface.
8．Thousands and thousands of animals live in rainforests.
9．Many of them live in the trees over 30 meters from the ground.
10．In fact, water makes up the largest part of the human body.
11．We must save every drop of water.
海绵宝宝之父去世
12．But now they have less and less land to live on.
13．…, but they feed on the smallest a animals.
14．They are in danger now.
二、单词和语法讲解
1．形容词和副词的比较级和最高级的构成：
英语里，形容词和副词有三个比较等级，即原级、比较级和最高级。
（1）一般在词尾加-er构成比较级，加-est构成最高级。如：
long-longer-longest
cold-colder-coldest
（2）以e结尾的直接在其后加-r变成比较级，加-st构成最高级。如：
nice-nicer-nicest
large-larger-largest
（3）只有一个辅音字母结尾的重读闭音节词，要双写最后一个辅音字母再加-er变成比较级，加-est构成最高级。如：
hot-hotter-hottest
thin-thinner-thinnest
（4）以辅音字母加y结尾的词，先将y变i，再加-er构成比较级，加-est变成最高级。如：
early-earlier-earliest
heavy-heavier-heaviest
下面是一个规律口诀：
比较级要变化，一般词尾加-er；
词尾若有哑音e，直接加r就可以；
一辅重读闭音节，辅音字母要双写；
辅音字母加上y，要把y变成i；
最高级后加est，前面加the莫忘记。
2．形容词和副词的比较级和最高级的用法：
I. 比较级：两者相比较，一个比另一个更……一些。
比较级＋：……比……较为。即：
A ＋系动词＋形容词比较级＋than＋B
His brother is younger than I（me）. 他弟弟比我年轻。
Beijing is more beautiful than Wuhan. 北京比武汉更漂亮。
心想事成英文 注意：
（1）在比较级前有时可加一些状语如much, a lot, a little, still, even等以示强调或加强语气。
This box is a little heavier than yours. 这个箱子比你的要稍重一些。
This movie is much more interesting than that one. 这部影片比那部有趣得多。
（2）表示两者中“较……的那一个”时，应该是特指，比较级前往往要用定冠词the。
She is the cleverer of the two. 她是两个孩子中较聪明的那个。
Give me the smaller of the two apples. 给我那个小苹果。
（3）两个比较级用and连接，表示“越来越......”
better and better 越来越好 more and more expensive 越来越贵
（4）如果比较对象相同，第二个比较对象可以用that/tho代替。that代替单数或不可数名词。
The weather in Beijing is warmer than that in Harbin. 北京要比哈尔滨暖和。
Ⅱ. 同级比较：表示两者比较，程度相同，意思是：……和……同样的……。
（1）as... as： ……和……同样的……。 即：
A+动词+as+形容词原级+as+B.
My uncle is as tall as your father. 我叔叔和你父亲一样高。
My dog is as old as that one. 我的狗与那个狗一样大。
（2）not as/so ... as ……不如……
A...＋not＋as＋形容词原级＋as＋B 表示A，B 两者程度不同，即“A不如B那么……”。
My uncle is not as tall as your father. 我叔叔不如你父亲高。
Tom is not as honest as John. 汤姆不如约翰诚实。
Ⅲ. 形容词最高级：用于三者或三者以上的人或事物之间比较，其中一个“最……”
A + is + the + 形容词最高级 + in/ of 短语
⑴ 形容词最高级前一般要用定冠词the。
⑵ 形容词最高级句型中一般有一个表示比较范围的介词短语：of＆in 短语
①of + 一群人或事物的代词或名词
②in + 每一单位或场所的名词
She’s the youngest of the three children.
The picture is the best of all in the book.
附：形容词和副词的比较等级及用法口诀:
一者比较用原级。比较级限二者比。三者三者往上比，最高级的用法起。
若要比项掌握齐，比较范围要搞细。比较级别句型记，做出句子没问题。
若甲乙程度相同，as…as 结构体。甲某方面不及乙，用 not as表示。
上述内容全记起，比较等级谈完毕。
3．think about, think of, think over的用法
（1）think about意为“考虑，思考”，与think of同义。如：
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People without a job try not to think of/ about the future.
diplomatic 没有工作的人尽力不去想将来的事。
What do you think about/ of? 你在想什么？
（2）think of作“想起，想到，认为”时，与think about不同。如：
She often thinks of her friend, Anna. 她常常想起她的朋友安娜。bandaged
What do you think of the film? 你认为这部电影怎么样？
（3）think over意为“仔细考虑，思考”，over为副词，代词应放在其前。如：
I've thought it over for a long time. 我已认真考虑那件事很久了。
Let me think over this difficult problem. 让我仔细思考这个难题。
4．keep的用法
（1）不归还，保留，保存。如：listen to this
How long can I keep it? 我可以借多少？
（2）keep +sb. /sth. +adj. 使某人/某物处于某种状态。如：
Put on my coat. It'll keep you warm. 穿上我的外套，它会让你暖和些。
We must keep our classroom clean and tidy. 我们必须保持教室干净整洁。
（3）keep on doing sth. 坚持做某事，反复做某事。如：
I keep on working. 我一直在工作。
（4）喂养，饲养
The boy likes to keep dogs. 那男孩喜欢养狗。
They keep a lot of hens. 他们养了很多母鸡。
katana They keep cows on their farm. 他们在农场养牛。
三、课文讲解
1．The hens are much smaller than the cows. 母鸡比奶牛小得多。
