Unit13 常识梳理1. at the bottom of the river 在河床底部2. be full of the rubbish 充满了垃圾3. throw litter into the river 把垃圾扔入河中4. play a part in cleaning it up 尽一份力把它清理干净5. land pollution 土地污染6. fill the air with black smoke 使空气中充满了黑烟7. cut down air pollution 降低空气污染8. make a difference 产生影响17. take action 采取行动18. turn off 关掉19. pay for 付费20. add up 累加21. use public transportation 用公共交通22. recycle books and paper 收购书和废纸23. use paper napkins 用纸巾24. turn off the shower 关掉喷头25. ride in cars 开车出行1.Even the bottom of the river was full of rubbish.即便河底都充满垃圾。2.Everyone in town should play a part in cleaning it up.城里的每一个人都应当尽一份力把它清理干净。3.The air is badly polluted because there are too many cars on the road these days.空气被紧急污染由于现在路上的汽车太多了。4.To cut down air pollution, we should take the bus or subway instead of driving.为了降低空气污染，大家应当乘坐公汽或地铁而不是开车。5. I used to be able to see stars in the sky.我过去能在天空中看到星星。6. The air has become really polluted around here. Im getting very worried.这儿的空气真的已经被污染了，我很担忧。
7. No scientific studies have shown that shark fins are good for health.没科学研究说明鱼鳍对大家的健康有好处。03词语精讲1. advantageadvantage是名词，意为优点；好处；有利条件 。比如：This bicycle has many advantages. 这辆自行车有很多优点。Studying English has many advantages. 学英语有很多好处。disadvantage是advantage的反义词，意为缺点；弊病；不利条件。比如：When you visit France, it is a disadvantage if you cannot speak French.当你访问法国时，假如你不会讲法语，那可是个不利条件。2. instead ofinstead of是介词短语，意为代替，而不是，后面可以跟与前面并列成分相应的名词、代词、动词|ing形式等作为介词宾语。比如：He went to the cinema instead of going to school.他去了电影院而不是学校。(1) instead作副词，意为代替，而不是，常用作状语。比如：He is tired. Let me go instead. 他累了，让我替他去吧。She never studies. Instead, she plays tennis all day.她从不学习，而是整天打网球。(2)instead和instead of的辨析：instead是副词，后面不接其他的词，通常情况下可不译出，一般放在句首或句末，在句首时常用逗号隔开，表示前面的事没做，而做了后面的事。比如：He didnt go to school. Instead, he went to the cinema.他没去学校，相反他去了电影院。Instead of lending a hand, he laughed at us.他不只没帮大家一把，反而嘲笑大家。3. cut offcut off是固定搭配，意为切除；切掉。比如：The slide cut off the valley from the rest of the world.山崩切断了这个山谷与外面的联系。动词 + off构成的短语有：take off 起飞，脱下 put off 推迟turn off 关闭 get off 下车fall off从掉下来 break off终止pay off 付清4. make a differencemake a difference意为起用途，有影响。比如：The fact that I can now organize my own time makes a big difference.目前我能自己安排时间了，这对我有非常大有哪些用途。Whatever you can do can make a difference.无论你能干什么，都会带来不同。5. the number ofthe number of意为的数目，后接可数名词复数，谓语动词用单数形式。比如：The number of people speaking Chinese is larger than that of those speaking English.说汉语的人数要大于说英语的人数。a number of 意为很多，后面接可数名词的复数形式，谓语动词用复数形式。number前面可以用large，great，small等修饰，构成a large number of; a small number of等。比如：I have a number of letters to write. 我有很多信件要写。A large number of students in our school are from the countryside. 大家学校很多学生来自农村。A small number of students in our class went swimming yesterday.昨天大家班一小部分学生去游泳了。6. althoughalthough的意思等于though，意为尽管，虽然，用来引导让步状语从句。它所引导的从句不可以与并列连词but; and; so等连用，但可以和yet; still等词连用。比如：Although he lives alone, he doesnt feel lonely.= He lives alone, but he doesnt feel lonely.虽然他自己住，但他并不感到孤独。There is air all around us, although we cannot see it.虽然大家看不见空气，但空气却存在于大家的周围。although与though的辨析：(1) 用作连词，表示虽然，二者可以互换用，但although比though更为正式。比如：Though/Although it was raining, we still went there.虽然下着雨，但大家还是去了那里。(2) although一般不需要作副词，而though可用作副词，且一般放在句末（不放在句首），意为可是，不过。比如：Its hard work; I enjoy it, though.工作非常辛苦，可是我非常喜欢。We all tried our best. We lost the game,though.大家都尽力最大努力，但大家还是输了。(3) 在as though(仿佛，仿佛)，eventhough(即便，即使)等固定短语中不可以用although。比如：He talks as though he knew everything. 他夸夸其谈，仿佛无所不知。