问题 选择题

下列实验方案中,可行的是[ ]

A.按溶解、过滤、蒸发的操作顺序分离CaCl2、CaCO3的混合物

B.将白醋滴在润湿的pH试纸上,测定其pH

C.用氢氧化钠溶液除去CO2中的HCl气体

D.用BaCl2溶液除去KNO3溶液中少量的K2SO4

答案

答案:A

阅读理解

阅读理解。

    Our factories and homes burn coal and oil. Every year we have forest fires somewhere. Many scientists

believe that the weather is changing.

    The earth will perhaps be warmed by about 7℃ at the South Pole (极) and the North Pole. The ice will

be melt (融化). The sea level (平面) will rise by about 7 meters. As a result, water will cover cities like

London, Tokyo and New York. Some ports (港口) and towns along the coasts will disappear under water.

    Some other scientists think that the dust, smoke and pollution from coal, wood and oil fires will block

out (封闭) the ultraviolet rays (紫外线). Then the earth will become colder and great sheets of ice will

cover Europe and North America. 

    When chemicals in the air mix with rain, we have acid (酸) rain. Acid rain can bring us great harm. It

destroys (破坏) forests and kills life in lakes and rivers.

    People are beginning to see how serious the problem is. They find it important to work with nature

instead of against it. They are trying to save the earth in many different ways. But one of the most important

things to do is to make people understand that saving the earth is saving ourselves.

1. Some scientists believe that            . [ ]

A. the earth is growing warmer

B. we need coal in our forests

C. we can find oil in our forests

D. we have to burn down the forests every year

2. Ice at the poles will             if the earth gets warmer. [ ]

A. become thicker by seven meters

B. cover cities like London and Tokyo

C. raise the sea level by 7 degrees

D. become water and make the sea rise

3. Acid rain can            . [ ]

A. bring great changes in our weather

B. kill pests (害虫) in lakes and forests

C. kill the fish in rivers and lakes

D. cover Europe and North America

4. What can we learn from the third paragraph? [ ]

A. The dust together with pollution from coal, wood and oil fires will bring us more heat from the sun.

B. The ultraviolet rays will come more because of the dust and pollution from fires.

C. According to the scientists, the change in weather hardly has anything to do with the pollution.

D. As a result of the dust and pollution from coal, wood and oil fires, the earth will become colder.

填空题