问题 选择题

古语说:“人要实,火要虚.”此话的意思是做人要脚踏实地,才能事业有成;可燃物燃烧要架空一些,才能燃烧更旺.“火要虚”的目的是(  )

A.降低可燃物的着火点

B.增大空气中氧气的含量

C.升高可燃物的着火点

D.增大可燃物与氧气的接触面积

答案

可燃物架空一些,可使空气容易进入而增大可燃物与空气的接触面,氧气与可燃物接触更充分;“火要虚”能使可燃物与空气中氧气接触更充分,燃烧更完全才能燃烧更旺;此做法不能改变可燃物的着火点等物质固有属性及空气中氧气的含量;

故选D.

阅读理解

阅读理解。

     "An apple a day keeps the doctor away." Well, milk may work in the same way!

     Milk is the natural food for mammalian (哺乳动物) babies. It helps them grow strong because it is rich

in protein (蛋白质), calcium (钙) and vitamins. Milk can also help you sleep better because it calms you

down.

     But remember to drink milk with care. Find out how old the milk is. Make sure it is fresh and hasn't gone

bad. Don't drink milk when your stomach is empty. Eat some bread or corn at the same time. That'll help

you take in more protein and vitamins.

     Doctors say teens need at least 500ml of milk a day. That's two or three cups. Milk-drinking started long

ago, as early as 6,000-8,000BC. At that time people started to keep cows, sheep and goats to get their milk.

Of course what you drink today isn't that fresh from the cow. People cool the fresh milk down to 40℃ to

stop the bacteria (细菌)growing. In factories, milk is pasteurized (灭菌) to stop it growing bad. After

disinfections (消毒) and packaging, it goes to the supermarkets.

     Yoghourt also comes from milk. People make some special bacteria to change the taste of milk and

make the nutrients (营养) in it easier for people to take in. Maybe that's why it's getting more popular

with people!

1. Milk helps people grow strong because it is rich in _____. [ ]

A. Calcium

B. protein

C. vitamins

D. A, B and C

2. The sentence "An apple a day keeps the doctor away." tells us that _____. [ ]

A.the doctor likes to eat apples every day

B. the doctor doesn't like apples at all

C. the doctor eats an apple each day

D. apples are good for our health

3. When you drink milk, you'd better _____. [ ]

A. find out when the milk was produced

B. make sure it's fresh and hasn't gone bad

C. not drink milk when your stomach is empty

D. do all of the above

4. Why is it better to eat some bread or corn while drinking milk?  [ ]

A. Our body can take in more protein and vitamins in this way.

B. That'll help us grow taller and stronger.

C. That'll help us taste milk better.

D. We'll still feel hungry without eating some bread or corn. 

5. Which of the following statements is true? [ ]

A. One cup of milk is good enough for teens each day.

B. Drinking milk is likely to make teens sleepy.

C. To stop the bacteria growing, people cool the fresh milk down to 40℃.

D. Yoghourt is one kind of milk which has gone bad

单项选择题