When we look at a picture of Earth from space，there are areas of green，blue，and white.Most people will recognize（辨認） that the green is land，the blue is water，and the white is clouds.Taken as a whole，Earth is mainly blue.That is because of the amount（數量） of water it has that covers the surface.
So，how much of Earth is water？About 71% of Earth's surface is covered in water.Of that 71%，the oceans hold 96.5% of the water.This water found in oceans is all salt water.The remaining 3.5% of the water is fresh water，which can be found in lakes，rivers，glaciers（冰川），and in the ground.Fresh water is what people use for farming，raising animals，drinking，and daily activities such as taking showers and washing clothes or dishes.
Does the amount of water stay the same？For the most part，yes.Water on Earth is part of a closed system （系統(tǒng)）.That is，water is always moving and changing forms between ice，liquid，and gas.The form of the water changes all the time，but the total amount of water on Earth remains the same.
If Earth is not necessarily running out of water，why are people worried？Why do we need to think about saving water？First，humans can only use fresh water，which is only 3.5% of all of Earth's water.Second，of this 3.5%，only 1% is available for human use.Most fresh water is found in glaciers far from where anyone lives.Third，the amount of water that is useful for humans is being used faster than it can be cleaned and put back into the environment.
Now，knowing the facts about water，it is our job to make sure we use Earth's water in a good way.
（1）The remaining 3.5% of the water on Earth CAN'T be found in AA.
A．oceans.
B．lakes.
C．glaciers.
D．rivers.
（2）What does the writer mean by saying "Water on Earth is part of a closed system."？ BB
A．The amount of water becomes smaller.
B．The amount of water stays the same.
C．The amount of water keeps changing.
D．The amount of water becomes larger.
（3）What can we learn from Paragraph 4？ CC
A．Humans can use all the water on Earth.
B．Most fresh water is found in the ground.
C．Humans can't use 2.5% of the fresh water easily.
D．Water can't be cleaned and put back into the environment.
（4）What is the main idea of the passage？ CC
A．Why Earth is in different colors.
B．Who uses the most water on Earth.
C．The amount and types of Earth's water.
D．How to use water in a good way.
【考點】說明文；環(huán)境保護．
【答案】A；B；C；C
【解答】
【點評】
聲明：本試題解析著作權屬菁優(yōu)網所有，未經書面同意，不得復制發(fā)布。
發(fā)布：2024/4/20 14:35:0組卷：25引用：6難度：0.5
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