问题 选择题

工业上常将固体燃料粉碎或把液体燃料喷成雾状再燃烧,其目的是

A.增加空气中氧气的体积分数

B.降低可燃物的着火点

C.延迟燃料燃烧的时间

D.增加燃料与氧气的接触面积

答案

答案:D

题目分析:使燃料充分燃烧注意两点:燃烧时要有足够多的空气,燃料与空气有足够大的接触面。燃料不充分燃烧的后果:产生的热量减少,浪费资源,产生大量的CO等物质污染空气,所以工业上常将固体燃料粉碎或把液体燃料喷成雾状再燃烧,其目的是:增加燃料与氧气的接触面积。故选D

阅读理解

We can all contribute to a greener world.Just follow these ten golden rules:

●Stop getting junk mail.Billions of junk mail can be sent every year.Half of it is never opened.Get-your name off mailing lists.If 100,000 people stopped getting junk mail today, it would save 150,000 trees a year.

●Stop reading newspapers.All over the world, millions of newspapers are thrown away every day, 44 million newspapers in the USA alone —that's half a million trees a week.Either recycle your newspapers or read the hews online.

●Buy clothes made from organic materials.Conventional cotton farming seriously pollutes the environment, most of which uses chemical pesticides (农药) and fertilizers. Organic is better!

●Switch to solar energy.In one day, the sun will provide enough energy to power the planet.Why aren't we using it?

●If you have to drive, share the ride.Most cars in the USA have only one occupant.Also, 25 percent of car rides are less than 1.5 kilometres.Get out and walk!

●Unplug your PC, TV and VCR.Simply turning them off isn't enough.Sets left on standby are still using 25 percent of their power.

●Hold on to your balloons.Helium-filled balloons which fly away usually end up in a lake or river, where they can choke aquatic (水生的) creatures.Save your balloons and use them again.Or better still, don't use them at all.

●Feed the birds.Wild birds need food, especially in v/inter when other sources can be scarce.The greater the range of foodstuffs you put out for them, the more types of birds you will attract.

●Plant a garden at your school.Learn the connection between the land and the table.Plant vegetables to eat, flowers to admire and trees to improve the air.

小题1:.

What is the main purpose of the passage?

A.To provide some health advice on how to work.

B.To suggest some ways how to make full use of solar energy.

C.To advise protecting environment and saving energy.

D.To advise on how to recycle waste and save energy.小题2:.

.The underlined expression "left on standby" in the sixth rule means__   __.

A.ready to start and use electricity

B.ready to be turned off

C.ready to be repaired

D.ready to be.put away小题3:.

.Which of the following will NOT protect trees from being cut down to make paper?

A.Not buying newspapers.

B.Don't accept junk mail.

C.Read your newspaper online.

D.Read only one newspaper.

单项选择题