阅读理解。
Sometime early in the next century,human beings will move to Mars.They will live there for
about a year,and then will be replaced with another group of pioneers.Building the base on
Mars will advance our knowledge of the solar system and aid in our understanding of the earth.
We already know that Mars resembles the earth in many aspects:general size,presence of
water,length of day,range of temperatures.These resemblances have caused many ?people? to
consider a centuries?long project:to terraform Mars.Terraforming means altering a planet's
surface so that Earth's life forms can survive there.This concept,previously found only in science
fiction is now being seriously considered by scientists.
Terraforming Mars is theoretically simple:add nitrogen and oxygen to the atmosphere;pump
water to the surface;and add the earth's plants and animals in the order in which they developed
on Earth.But it will take at least 300 years.
Some people think that such a project is too huge for ?humans? to undertake,but there are
very good reasons to make the attempt.The earth now contains some 6 billion ?people?,and
no one has any idea of how many humans the earth can support.Our very existence and numbers
are threatening many other species.We also have had some experience with terraforming our
own planet:altering the landscape,the atmosphere and the climate.Currently terraforming earth
has become a wiser activity as we try to control global warming,air and water pollution,and
preserve some natural living places.
While the possibility of such a project is small,it is not impossible.Even if earth bound societies
come and go in the next 300 years,the project can continue through the work of the Mars settlers
without the need for constant backing from the earth.
The future existence of all the people in our world may very well depend upon our ability to
terraform Mars.
1.What would be the bes ttitle for this passage?_____
A.Terraforming Mars
B.Saving the Earth
C.Travelling to Mars
D.A NewlyFound Place
2.What does the underlined word " altering" mean in the second paragraph?_____
A.Warming.
B.Changing.
C.Planting.
D.Building.
3.According to the passage, the main purpose ofter raforming Mars is to_____.
A.do some scientific research work
B.find out its similarity to earth
C.avoid the dying away of many other species
D.find on Mars livingplace for the increasing humanbeings
4.The main reason for causing many people to consider terraforming Mars is that_____.
A.there are some resemblances between Earth and Mars
B.terraforming Mars is theoretically simple
C.we have had some experience with terraforming our own planet:Earth
D.the development of science and technology is very rapid
5.What's the author's attitude towards the project? _____
A.Optimistic.
B.Negative.
C.Skeptical(怀疑的).
D.Objective.