问题 填空题

活动卡中有一学生实验活动:在空塑料瓶的底部扎一个小孔,用手指堵住小孔,向瓶中注满水,并旋上盖子。然后,松开手指,水      从瓶中流出,如果将盖子旋开,水       从瓶中流出(均选填“能”或“不能”)。这一实验与著名的     实验一样,证明了大气压强的存在。

答案

不能;能;马德堡半球  

向瓶中注满水,并旋上盖子,则瓶外气压大于瓶内水压,所以水不能从瓶中流出.如果将盖子旋开,水面与大气压相通,瓶内气压与瓶外气压平衡,所以水在液体压强的作用下,会从小孔射出来.这一实验与著名的马德堡半球实验一样,证明了大气压的存在.

故答案为:不能;能;马德堡半球.

阅读理解

阅读理解。

    Between now and then many changes will take place in this century. But what will the changes be? The

population is growing fast. There will be many people in the world and most of them will live longer than

people live now.

    Computers will be much smaller and more useful, and there will be at least one in every home. And

computer studies will be one of the important subjects in school then.

    People will work fewer hours than they do now, and they will have more free time for sports, watching

TV and travel. Traveling will be much cheaper and easier. And many more people will go to other countries

for holidays.

    There will be changes in our food, too. More land will be used for building new towns and houses for

all the people. Then there will be less room for cows and sheep, so meat will be more expensive. Maybe

no one will eat it every day. Instead they will eat more fruit and vegetables. Maybe people will be healthier.

Work in the future will be different, too. Dangerous and hard work will be done by robots. Because of this,

many people will not have enough work to do. This will be a problem.

1. In the future there will be ______. [ ]

A. much more fruit

B. more people

C. less vegetables

D. less people

2. Every family will have at least one ______ in this century. [ ]

A. robot

B. cow

C. TV net

D. computer

3. In the future, people don't have to ______.[ ]

A. work long hours

B. work fast

C. walk on foot

D. eat meat

4. One big problem in the future is that ______. [ ]

A. many people don't have to work

B. many people will not be able to find work

C. people have to work fast

D. all the work will be done by robots

5. In the future, maybe no one will eat ______ every day, instead they will eat ______. [ ]

A. fruit; meat

B. vegetables; meat

C. meat; fruit and vegetables

D. meat; hot food and desserts (甜食)

单项选择题 A1型题