您正在看的高中二年级是:Saving the earth。 ied out.这些动物已经绝种。

　　The fire died out。火熄灭了。

　　That style of music died out ten years ago.那种音乐十年前就听不到了。

　　Elephants would die out if men were allowed to shoot as many as they wished.如果允许人类随意射杀大象，这种动物就会灭绝。

　　▲ an average of是一个固定词组，意为“平均有。。。”后一般跟数次 。

　　An average of ten students are absent each day.每天平均有十名学生缺席。

　　The new car factory will produce an average of 200,000 cars each year.这个新汽车厂每年平均将生产20万辆汽车。

　　An average of 4 people were killed or injured in the traffic accidents each day last year.去年平均每天有4人在车祸中丧生或受伤.

　　3.By 1985 this had risen to one per day. Between 1980 and 2000 we may lose another half a million different kinds of living things. 到1985年,这个数字上升到每天灭绝一种.在1980到2000年之间我们可能会再失去50万种不同的生物.

　　▲ by用来引导时间状语时,意为”到…时侯为止”, “在…时侯之前”,句中的谓语动词用完成时态,如引导的是过去的时间状语,谓语动词用过去完成时态,如引导的是将来的时间状语,则用将来完成时态.

　　By the end of last year,we had learned 1000 English words.到去年年底为止,我们已学会了1000英语单词.

　　By next Friday,I shall have finished the work.到下周五,我将完成这项工作.

　　Surely Robert must have returned by now.现在罗伯特肯定已经回来了.

　　【注】当谓语动词由be来充当时,多用一般时态.

　　By then he was more than fifty years of age.到那时,他已经五十多岁了.

　　You must be hungry by this time.现在你肯定饿了.

　　By next morning,he was nearly through with it.到第二天早晨,他差不多完成了.

　　▲ another意为”另一”,当和数词连用时,作”还”,”再”,”又”解释.

　　Alice continued to remain in London for another four or five days.艾利斯在伦敦又呆了四五天.

　　The strike may last another six months.罢工可能还要持续六个月.

　　Where shall we be in another ten years?再过十年以后我们会在哪里?

　　▲per day 意为”每天”,相当于each day

　　4.There are many reasons for animals dying out,but the most important one is the part that humans have played.动物的灭绝有很多原因,但是最重要的原因是人类所起的作用.

　　▲reason意为”原因”,后接介词for或why引导的从句,也可以接that从句.

　　The reason for the flood was all that heavy rain.洪水的原因完全在于那场暴雨.

　　The reason that (why) he died was lack of medical care.他的死亡原因是医治不够.

　　▲当前面有the reason或the reason why时,后面一般不应用because引导从句,而应用that来引导表语从句.

　　The reason for my absence was that I was ill.我缺席的原因是我病了.

　　The reason why he was late was that he had to send his mother to hospital.他迟到的原因是他必须送母亲去医院.

　　▲the part that humans have played意为”人类所起的作用”. That是关系代词,引导定语从句修饰 the part,词组play a part作”起作用”解释.

　　They are playing an increasingly important part in in safeguarding the peace.他们对保卫和平起着越来越重要的作用.

　　The part played by religion was very great.宗教所起的作用是很大的.

　　Especially in Brazil, the Negroes have played a most important part in the development of the nation.特别在巴西,黑人在国家的发展中起着最重要的作用.

　　Such strikes have played an important part in the development of the trade union movement.这种罢工对工会运动的发展已经起到了重要的作用.

　　▲human是可数名词,a human或 a human being指一个人,复数形式是 humans,也可以说 human beings

　　In the story human beings were replaced by robots.这个故事中,人被机器人取代.

　　Wolves will not usually attack humans.狼通常不会向人进攻/

　　5.First,many animals have been killed for food.Second, many of the places where these animals used to live have been destroyed.首先,许多动物被捕杀供食用,其次,动物原先居住的很多地方被毁坏了.

　　▲ 介词for在此处表示目的

　　①We went to the bar for a drink.我们去酒吧喝酒.

　　②Is that cake for eating or just for looking at?那蛋糕是吃的还是仅用来看的?

　　③An altimeter is used for measuring height above sea-level.高度计是用来测量海拔高度的.

　　④Robert is going to get material for a new book..罗伯特准备为写一本新书去收集材料.

　　⑤They made her go to the hospital for a check-up.他们使她去医院作了一次检查.

　　【注】for表示目的时,后接名词,不接动名词,但是当 for后面表示的是某物的用途时,可接动名词短语.如例句②③

　　6.Dry lands have been watered. Wet landshave been turned into fields.Forests have been cleared.旱地被灌溉了.湿地变成了田野.树林被砍伐光了.

　　▲ land表示”陆地”,”土地”时是不可数名词,表示”地产”,”田产”时可用复数形式,表示”国家”,”地区”时,也是可数名词.

　　They owned both houses and lands.他们拥有房地产.

　　These lands belong to my elder brother.这些地方是我哥哥的.

　　Workers of all lands,unite.全世界无产者,联合起来.

　　He has visited many distant lands.他到过许多遥远的国家.

　　▲ water此处用作动词,意为”浇水”, “灌溉”.

　　A new reservoir has been built to water 80 percent of the farmland.新修了一座水库,是百分之八十的农田都得到灌溉.

　　The Shanxi plain is watered by the Fen River which runs thro