Manned bases on the Moon or Mars for example， have long been a dream of many. There is a natural desire to explore as far as we can go， and also to extend humanity's presence on a permanent or at least semi-permanent basis. In order to do this， however， it is necessary to adapt to different extreme environments. On the Moon for example， a colony must be self-sustaining and protect its inhabitants from the airless， harsh environment outside. Mars， though， is different. While future bases could adapt to the Martian environment over time there is also the possibility of modifying the surrounding environment instead of just co-existing with it. This is the process of terraforming - adjusting Mars' atmosphere and environment to make it more Earth-like. But the bigger question is， should we？ One of the main issues is whether Mars has any native life or not and if it does， should it be preserved as much as possible？ If the answer is yes， then large-scale human settlements on Mars should be completely off-limits. Small colonics might be fine， but living on Mars should not be at the expense of any native habitats， if they exist. If Mars is home to any indigenous life， then terraforming should be a non-issue；it simply should not be done. What if Mars is lifeless？ Even if no life exists there， that untouched and unique alien environment needs to be preserved as it is as much as possible. We've already done too much damage here on our own planet. By studying Mars and other planets and moons in their current natural state， we can learn so much about their history and also learn more about our own world. We should appreciate the differences of other worlds instead of just transforming them to suit our own ambitions.（1）What is the best title for the text？ ____

As we continue to explore farther out into our solar system and beyond，the question of humans living on other planets often comes up. Manned bases on the Moon or Mars for example， have long been a dream of many. There is a natural desire to explore as far as we can go， and also to extend humanity's presence on a permanent or at least semi-permanent basis. In order to do this， however， it is necessary to adapt to different extreme environments. On the Moon for example， a colony must be self-sustaining and protect its inhabitants from the airless， harsh environment outside.
    Mars， though， is different. While future bases could adapt to the Martian environment over time there is also the possibility of modifying the surrounding environment instead of just co-existing with it. This is the process of terraforming - adjusting Mars' atmosphere and environment to make it more Earth-like. But the bigger question is， should we？
    One of the main issues is whether Mars has any native life or not and if it does， should it be preserved as much as possible？ If the answer is yes， then large-scale human settlements on Mars should be completely off-limits. Small colonics might be fine， but living on Mars should not be at the expense of any native habitats， if they exist. If Mars is home to any indigenous life， then terraforming should be a non-issue；it simply should not be done.
    What if Mars is lifeless？ Even if no life exists there， that untouched and unique alien environment needs to be preserved as it is as much as possible. We've already done too much damage here on our own planet. By studying Mars and other planets and moons in their current natural state， we can learn so much about their history and also learn more about our own world. We should appreciate the differences of other worlds instead of just transforming them to suit our own ambitions.
（1）What is the best title for the text？ ____
A. A Is there life on Mars？
B. Can we adapt to Mars？
C. Should we terraform Mars？
D. Are Mars and Earth So Different？
（2）What does the author think we should do if life is found on Mars？ ____
A. Ensure that it's not harmed.
B. Negotiate with the Martians.
C. Change the unpopulated regions.
D. Assess the advantages and disadvantages.
（3）What does the underlined word "indigenous" in paragraph 3 mean？ ____
A. Complex.
B. Native.
C. Foreign.
D. Intelligent.
（4）How does the author develop his ideas in the text？ ____
A. By referring to others' research.
B. By evaluating different planets.
C. By justifying the benefits of terraforming.
D. By arguing in support of one viewpoint.