Should we try to contact and make friends with other beings in the universe? Certainly not，says British physicist Stephen Hawking．
“If aliens（creatures from other planets）ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn out very well for the Native Americans,’’ said the 68-year-old disabled scientist in a new Discovery documentary (纪实性电视节目) on April 25．
The program pictures an imagined universe where other life forms in huge spaceships hunt for resources after using up all those on their home planets．
“Such advanced aliens would perhaps become nomads(游牧民)，looking to conquer and colonize whatever planets they can reach，”warned Hawking．
On the probability of other life forms existing, he says, “To my mathematical brain, the numbers alone make thinking about aliens perfectly reasonable.”
Hawking’s concerns have frightened some people and been met with disagreement from other researchers．Paul Davies, author of the book Renewing Our Search for Alien Intelligence，thinks Hawking’s reasoning is wrong.
He argues that since Earth is about 4.5 billion years old，if intel1igent life is likely , communities of other beings may have been there for a very long time．
“If resources are the factor, then at least one group of aliens would surely have visited Earth as a destination mil1ions of years ago．
Even if other life forms do come to Earth in the near future, Davies believes comparisons with are wide of the mark(离谱的).
68. What is the article mainly about? 
A. Other life forms coming to our planet．
B. Scientific evidence of other life forms．
C. Earth as the only place where human beings can survive．
D. Hawking’s belief that other life forms may exist in the universe．
69. Which of the following ideas is opposed to Hawking’s view?
A. Other life forms exist in the universe．
B. 0ther life forms may be more intelligent than human beings．
C. We should try to contact other 1ife forms from other planets．
D. Other life forms may exist in more than one part of the universe．
70. Paul Davies didn’t agree with Stephen Hawking ,believing that ________．
A. the universe is running out of resources
B. humans are the best creatures in the universe.
C. it is a good idea to avoid meeting with other life forms   
D. Davies doesn’t think it proper to compare aliens with Columbus
71. Hawking referred to Christopher Columbus as an example to ____．
A. inspire interest in the universe      
B. draw attention to other planets in the universe
C. warn people to watch out for other life forms
D. urge further exploration of the universe~