Water can be a liquid, a solid or a gas．When it is a solid, it may be as hard as rock．When it is a liquid, you can pour it out of a bottle．When it is a gas, you cannot see or pr feel it．
Water can change from one form to another easily．When we freeze water, it turns into ice．When we boil water, it turns into steam．When ice melts, it turns into water．When steam cools, it turns into water．The three forms of water are ice, steam and water．
Where does water come from? Water rises to the sky by the heat．Water vapour is formed．This rises and forms clouds in the air．When the clouds come near a mountain, they are forced to rise．As the clouds rise, they are cooled．The higher they rise, the more they are cooled．This causes more and more water vapour to condense(凝结)．In this way, the tiny drops of water in the clouds get bigger and bigger until they are heavy enough to fall to the earth as rain．
Some rain water which falls on the earth again rises to the sky by the sun's heat．Some of it sinks into the ground．It may be used up by thirsty plants．It may reach a well．Most of the water goes back to the rivers, seas and oceans．This process then starts all over again．This process is called the water cycle．
(1)
What are the forms of most matter?
[ ]
A．
solid, rock, ice．
B．
liquid, gas, solid．
C．
gas, rock, steam．
D．
water, ice, steam．
(2)
What may happen when the clouds rise?________．
[ ]
A．
The higher they rise, the more they are heated．
B．
The higher they rise, the more they are cooled．
C．
The higher they rise, nothing will happen．
D．
The higher they rise, the more they change into water．
(3)
The tiny drops of water in the clouds cannot be called rain ________ to fall to the earth．
[ ]
A．
until they are heavy enough
B．
until they get bigger enough
C．
before they are too heavy
D．
when they are heavy enough
(4)
Most of rain water which goes back to the rivers, seas and oceans is ________ by the sun's heat．
[ ]
A．
condensed
B．
forced to rise
C．
evaporated(蒸发)again
D．
changed into steam
(5)
According to the article, which of the following statements is true?
[ ]
A．
When water evaporates, we also say that is condenses．
B．
Most of the rain water which falls on the earth is evaporated again by the sun's heat．
C．
The higher the clouds rise, the smaller the tiny drops of water in the clouds get．
A plant makes its own food in its leaves. Water comes to the leaves through the roots (根). Air gets into the leaves through very small holes. The green coloring in the leaves uses the water and air to make food for the plant. It also needs sunshine because a plant can make food only when the sun is shining.
Animals and people could not live without green plants. They both eat plants. People and some animals also eat the meat of some animals, and these animals eat plants.
(1)
A plant gets food from its leaves.
( )
(2)
The sun uses the water and air to make food for the plant.
( )
(3)
A plant has very small holes in its leaves for water to come in.
( )
(4)
A plant can make its food when it is a sunny day.
( )
(5)
From the article we know that people can’t get food without animals.
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