When characters fall through the sky in cartoons，they often lie on clouds. What is a cloud？And what would it feel like to touch a cloud in real life？
    Believe it or not，many of us have already touched a cloud though we probably didn't realize it at the time. "Clouds are really little drops of water in the air，" says Kristina Pistone，a scientist from NASA. "If you've ever walked outside on a really①              day where you can't see very far，you're walking through a cloud，" Pistone said.That's because fog is just a kind of ②              that forms on the ground.
    According to the World Meteorological Organization，there are more than 100 kinds of clouds.But Pistone said that with a bit of practice，anyone can learn to recognize some of the more common clouds：

Altocumulus clouds（高积云）	They are white or gray round clouds.They look like the wool（羊毛）of sheep so they get the name"sheep backs".
Cumulonimbus clouds（积雨云）	They rise into towers and look like large flowers.
Cirrocumulus clouds（卷积云）	They are small，white clouds often appearing in lines.
Cirrus clouds（卷云）	They are thin，white pieces of clouds that lie across the sky.

Cloud color is also interesting.Black or dark clouds usually mean a storm is coming because they're so full of water that light can't pass through them.
    All of this is important for scientists to study because a lot of big white clouds help reflect（反射）heat back into space.云能对天气变化起作用。
    So the next time you see a sky full of white clouds，think about all the ways those little water drops might be affecting the world around us - not only by raining or snowing，but by changing the planet's temperature!

（1）将划线句子 When characters fall through the sky in cartoons，they often lie on clouds.译为汉语。

当卡通人物从空中坠落时，他们经常躺在云端。

当卡通人物从空中坠落时，他们经常躺在云端。

（2）在①②处填入适当的词语，每空限填1词。
①

foggy

foggy

②

cloud

cloud

（3）选出划线词汇 recognize 的汉语意思。

A

A

A.辨认
B.混淆
C.影响
D.遗忘
（4）选出与四种云相匹配的图片。
①Altocumulus clouds

B

B

②Cumulonimbus clouds

D

D

③Cirrocumulus clouds

A

A

④Cirrus clouds

C

C

（5）写出划线词汇 them 指代的内容。

Black or dark clouds.

Black or dark clouds.

（6）将划线句子"云能对天气变化起作用。"译为英语。

Clouds can play a role in climate change.

Clouds can play a role in climate change.