Water

Earth is like a bigblue marble.From high above the Earth and from the moon,the planet gleams andshines.The blue water in the oceans and seas of the Earth makes a

dramatic image.Thewhite clouds above the Earth add beauty to the picture.Water is the source ofthis beauty and the source of life on Earth.It is the reason people can live on

this planet. Wateris everywhere.(46)_______.It is in the soil,the ground that grows thefood.Water is in rock deep under the ground, in natural holding areas一in storage.In a

real sense,waterkeeps Earth alive.

Nature has anunchanging amount of water. Nature has a perfect system for recycling water.(47)_____.It falls as rain.Then it goes to one of three places.It might sinkslowly

through the soilinto the natural holding areas in the rock.(48)_______一by becoming vapor,or gas.It might runoff into streams,rivers and oceans.By itself,nature can keep

the balance andprovide plenty of clean water for us.Nature recycles water.

However,people causeproblems for this natural recycling system.Nature's recycling system can workwell(49)________.Some ways that people upset nature are easy to

understand.Forexample, dirty sewage（污水沟系统）water from homes and factories must not mix with drinking water.People get sick from drinking contaminated water.

Sometimes water fromfactories goes into streams and rivers.It enters into the groundwater. It canflow into lakes too.This kind of contamination from industry(waste water

from factories) canbe dangerous for people.If water contains poisons and chemicals,it ispoison.(50)________;some poisons kill people as well as birds andanimals.Without

knowing,people canupset nature's recycling system.

Lakes and rivers addbeauty to the world. People enjoy water for entertainment purposes,too. Peopleenjoy swimming and playing in the cool water of a lake in the summer.

They like to ride onboats on rivers.Many people enjoy catching fish in the rivers.They fish forfood and for sport.However,in some places,the water of the lakes and rivers is

no longer safe.Theserivers and lakes are contaminated.The fish are dying because of the chemicalsfrom farms and factories.People cannot swim in the polluted water._________（47）

A.Poison makespeople sick

B.It is in the airthat people breathe

C.We can not livewithout water

D.Water is usedagain and again

E.only if peoplework with the system and not against it