Preserve theEnvironment

Throughout historyman has changed his physical environment in order to improve his way of life.

With the tools oftechnology he has altered many physical features of the earth.He hastransformed

woodlands intofarmland,and made lakes and reservoirs out of rivers for irrigation purposes orhydroelectric

power. Man has alsomodified the face of the earth by draining marshes and cutting throughmountains to

build roads andrailways.

However,man'schanges to the physical environment have not always had beneficial results.Today,

pollution of the airand water is an increasing danger to the health of the planet.Each daythousands of tons

of gases come out ofthe exhausts of motor vehicles;smoke from factories pollutes the air ofindustrialized areas

and the surroundingareas of countryside.The air in cities is becoming increasingly unhealthy.

The pollution ofwater is equally harmful.In the sea,pollution from oil is increasing and iskilling enor-

mous numbers ofalgae（水藻）,fish andbirds.The whole ecological balance of the sea is being changed.

The same problemexists in rivers.Industrial wastes have already made many rivers lifeless.

Conservationistsbelieve that it is now necessary for man to limit the growth of technology inorder to sur-

vive on earth.Man has changedhis physical environment with a view to_________.

A.altering thephysical features of the earth

B.modifying the faceof the planet

C.improving hissurroundings'

D.bettering his wayof life