阅读理解

　　Without the atmosphere there would he no weather, no wind, rain, snow, or clouds. Air is all around us; we live at the bottom of a great ocean of air. It is invisible, but we can feel it when it moves. There are miles of air above us, pressing down with great weight on the earth and everything on it. Because air presses down on us from all directions at the same time, and because we are able to bear(忍受) this weight, we do not seem to feel it. But scientists have proved that air has this weight, and that anything that has weight creates(产生) a force called pressure. As changes in air pressure take place, they, make air move.

　　Air is a gas that expands (膨胀) when heated, gets lighter, and moves upward. When air is cooled, it gets heavier, sinks close to the earth's surface, and flows like water in a great river. As warm air rises, cold air rushes in to take its place. Thus winds originate(起源). The winds that blow high above us are caused by the warmer air running away from colder air. The wind we feel near the earth's surface is the heavy colder air trying hard to catch the warmer air. Changes in temperature cause the air to move. And of course there are many changes, so air movements are taking place practically all the time.

1．The first paragraph mainly tells us the causes of ________.

[　　]

A．why we don't feel air

B．why atmosphere is important to us

C．why there is air surrounding us

D．why there is air pressure

2．Air moves under such conditions that ________.

[　　]

A．there is air pressure

B．the air is heavy

C．air pressure doesn't remain the same all the time

D．air comes up and down

3．According to the passage, in same areas if farmers who grow grapes (葡萄) light fires in the early morning, that is because the farmers want to ________.

[　　]

A．drive away warm air

B．prevent cold air from coming to harm their plants

C．cause more wind

D．stop warm air running away

阅读理解

阅读下面短文，从每题所给四个选项中选出最佳答案。

　　Without the atmosphere there would be no weather, no wind, rain, snow, or clouds. Air is all around us; we live at the bottom of a great ocean of air. It is invisible, but we can feel it when it moves. There are miles of air above us, pressing down with great weight on the earth and everything on it. Because air presses down on us from all directions at the same time, and because we are able to bear(忍受) this weight, we do not seem to feel it. But scientists have proved that air has this weight, and that anything that has weight creates(产生) a force called pressure. As changes in air pressure take place, they make air move.

　　Air is a gas that expands(膨胀) when heated, gets lighter, and moves upward. When air is cooled, it gets heavier, sinks close to the earth's surface, and flows like water in a great river. As warm air rises, cold air rushes in to take its place. Thus winds originate(起源). The winds that blow high above us are caused by the warmer air running away from colder air. The wind we feel near the earth's surface is the heavy colder air trying hard to catch the warmer air. Changes in temperature cause the air to move. And of course there are many changes, so air movements are taking place practically all the time.

1．The first paragraph mainly tells us the causes of ________.

[　　]

A．why we don't feel air

B．why atmosphere is important to us

C．why there is air surrounding us

D．why there is air pressure

2．Air moves under such conditions that ________.

[　　]

A．there is air pressure

B．the air is heavy

C．air pressure doesn't remain the same all the time

D．air comes up and down

3．According to the passage, in some areas if farmers who grow grapes(葡萄) light fires in the early morning, that is because the farmers want to ________.

[　　]

A．drive away warm air

B．prevent cold air from coming to harm their plants

C．cause more wind

D．stop warm air running away

阅读下列短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。

　　Without the atmosphere there would be no weather，no wind，rain，snow，or clouds．Air is all around us；we live at the bottom of a great ocean of air．It is invisible，but we can fell it when it moves．There are miles of air above us，pressing down with great weight on the earth and everything on it．Because air presses down on us from all directions at the same time，and because we are able to bear this weight，we do not seem to feel it．but scientists have proved that air has this weight，and that anything that weight creates a force called pressure．As changes in air pressure take place，they make air move．

　　Air is a gas that expands(膨胀)when heated，gets lighter，and moves upward．When air is cooled，it gets heavier，sinks close to the earth's surface，and flows like water in a great river．As warm air rises，cold air rushes in to take its place．Thus winds originate(起源)．The winds that blow high above us are caused by the warmer air running away from colder air．The wind we feel near the earth's surface is the heavy colder air trying hard to catch the warmer air．Changes in temperature cause the air to move．And of course there are many changes，so air movements are taking place practically all the time．

1．the first paragraph mainly tells us the causes of________．

[　　]

A．why we don't feel air

B．why atmosphere is important to us

C．why there is air surrounding us

D．why there is air pressure

2．Air moves under such conditions that________．

[　　]

A．there is air pressure

B．the air is heavy

C．air pressure doesn't remain the same the time

D．air comes up and down

3．Which of the following pictures best tells the movements of warm air and cold air？

[　　]

4．According to the passage，in some areas if farmers who grow grapes light fires in the early morning，that is because the farmers want to________．

[　　]

A．drive away warm air

B．prevent cold air from coming to harm their plants

C．cause more wind

D．stop warm air running away

　　Without the atmosphere there would be no weather, no wind, rain, snow, or clouds. Air is all around us; We live at the bottom of a great ocean of air. It is invisible, but we can feel it when it moves. There are miles of air above us, pressing down with great weight on the earth and everything on it. Because air presses down on us from all directions at the same time, and because we are able to bear this weight, we do not seem to feel it. But scientists have proved that air has this weight, and that anything that has weight creates a force called pressure. As changes in air pressure take place, they, make air move.

　　Air is a gas that expands when heated, gets lighter, and moves upward. When air is cooled, it gets heavier, sinks close to the earth's surface, and flows like water in a great river. As warm air rises, cold air rushes in to take its place. Thus winds originate. The winds that blow high above us are caused by the warmer air running away from colder air. The wind we feel near the earth's surface is the heavy colder air trying hard to catch the warmer air. Changes in temperature cause the air to move. And of course there are many changes, so air movements are taking place practically all the time.

1．The first paragraph mainly tells us ________.

[　　]

A．that there is air pressure

B．why air is invisible

C．why there is air around us

D．that there is air around us

2．Air moves under such conditions that ________.

[　　]

A．there is air pressure

B．the air is heavy

C．air pressure doesn't remain the same all the time

D．air comes up and down

3．Which of the following pictures best tells the movements of warm air and cold air?

[　　]

A．

B．

C．

D．

4．Why do farmers who grow fruit trees make fires in the early morning?

[　　]

A．To drive away warm air.

B．To prevent cold air from coming to harm their trees.

C．To cause more wind.

D．To stop warm air running away.

Without the atmosphere there would be no weather, no wind, rain, snow, or clouds. Air is all around us; we live at the bottom of a great ocean of air. It is invisible, but we can feel it when it moves. There are miles of air above us, pressing down with great weight on the earth and everything on it. Because air presses down on us from all directions at the same time, and because we are able to bear (忍受) this weight, we do not seem to feel it. But scientists have proved that air has this weight, and that anything that has weight creates(产生) a force called pressure. As changes in air pressure take place, they, make air move.

Air is a gas that expands(膨胀) when heated, gets lighter, and moves upward. When air is cooled, it gets heavier, sinks close to the earth's surface, and flows like water in a great river. As warn air rises, cold air rushes in to take its place. 'Thus winds originate (起源). The winds that blow high above us are caused by the warmer air running away from colder air. The wind we feel near the earth's surface is the heavy colder air trying hard to catch the warmer air. Changes in temperature cause the air to move. And of course there are many changes, so air movements are taking place practically all the time.

The first paragraph mainly tells us the causes of

A．why we don't feel air　　　　　　　B．why atmosphere is important to us

C．why there is air surrounding us　　D．why there is air pressure

Air moves under such conditions that

A．there is air pressure              B．the air is heavy

C．air pressure doesn't remain the same all the time  D．air comes up and down

Which of the following pictures best tells the movements of warm air and cold air?

According to the passage, in same areas if farmers who grow grapes (葡萄) light fires in the early morning, that is because the farmers want to________________．

A．drive away warm air  B．prevent cold air from coming to harm their plants

C．cause more windD．stop warm air running away