问题 填空题

在一张白纸上用红颜料写一个字,把它拿到暗室里,只用绿光照射时,则白纸呈____色,红字呈_____色。色光三原色等比例混合得到    

答案

绿 ;黑 ; 白光

题目分析:白纸能反射所有的色光,当绿光照射时,它反射绿光,所以是绿色;而红字只能反射红光,当绿光照射时不能被反射,所以字就是黑色;色光三原色等比例混合得到白光。

点评:此题主要考查不透明物体的颜色及色光三原色等比例混合,属于基础知识,需要掌握.

单项选择题
阅读理解

阅读理解

     When a storm is coming, most people leave the area as quickly as possible and head for safety. But

there are a few people who will get into their cars and go straight for the center of the storm. These

people are willing to risk(冒……危险) being killed by floods or 100-kilometer-an-hour winds for the

excitement of watching the storm close up.

     "Storm  chasing (追逐 )"  is  becoming  an increasingly popular hobby (喜好) , especially in the

Midwest of the United States, where there are frequent storms between March and July. A storm chaser

begins the day by checking the Internet for the latest weather reports, and then drives up to 1 000

kilometers to where the storm will be and waits for it to develop.

   Although anyone can do it, storm chasing is extremely dangerous. The power of a big storm can throw

a cow into the air or destroy a whole house in seconds. Storm chasers are also often hurt in accidents

caused by driving in a heavy rain. If you are a beginner, it is much safer to join a group for storm- chasing

vacations during the storm season.

     Even then, storm chasing is not all adventure and excitement. "Storm chasing is 95% driving, " says

Daniel Lynch, who spends most of his summer storm- chasing. "sSometimes you can sit around for hours waiting for something to happen, and all you get is blue sky and a few light showers. "

However, for storm chasers, it is all worth it. "When you get close to a storm, it is the most exciting sight

you will ever see in your life, " says Jasper Morley. "Every storm is an example of the power of nature. It

is the greatest show on Earth. "

1. For storm chasing, the first thing storm chasers do  is to       .

A. head straight for the center of the storm

B. get into the car for safety    

C. wait patiently for the storm to develop

D. collect information about a coming storm

2. Beginners of storm chasing are advised         .

A not to drive in a heavy rain

B. to do it in an organized way

C. not to get too close to a storm

D. to spend more time on it in summer

3. By saying "it is all worth it" in the last paragraph, the author means that         .

A. storm chasing costs a lot of money

B. storm chasing is worth hours of waiting

C. efforts in storm chasing are well paid

D. a storm presents the greatest show on earth

4. What can we leam from the text?

A. Sometimes storm chasers get nothing but disappointment.

B. Many storm chasers get killed in the storms.

C. Storm chasing is becoming popular around the world.

D. Storm chasing is only fit for young people.