阅读下面短文并回答问题，然后将答案写到答题卡相应的位置上（请注意问题后的字数要求）。
[1] Have you ever had the wish to live another 100 years or more? Experts say that scientific advances will some day enable us to live tens of years longer than what is now seen as the natural limit of the human life span.
[2] “I guess we are knocking at the door of living longer,” said Michael Zey, a Montclair State University business professor and author of two books on the future. "I think by 2075 we will            _________________ and that’s a conservative estimate (保守的估计)."
[3]At the conference in San Francisco, Donald Louris, a professor at New Jersey Medical School in Newark said advances in using genes as well as nanotechnology (纳米技术) make it likely that humans will live in the future beyond what has been possible in the past. "There is a great push so that people can live from 120 to 180 years," he said.
[4]However, many scientists who specialize in ageing are doubtful about it and say the human body is just not designed to live past about 120 years. Even with healthier lifestyles and less disease, they say failure of the brain and organs will finally lead all humans to death.
[5]Scientists also differ on what kind of life the super aged might live. "It remains to be seen if you pass 120, you know; could you be healthy enough to have a good quality of life?" said Leonard Poon, director of the University of Georgia Gerontology Centre. "At present people who could get to that point are not in good health at all."
What is the main idea of the passage? (no more than 10 words)
_____________________________________________________________________
Please fill in the blanks in the second paragraph with proper words. (no more than 5 words)
____________________________________________________________________
According to Donald Louris, what will enable humans to live longer? (no more than 8 words)
_____________________________________________________________________
What does the word “it” (Line1,Paragraph4)probably refer to? (no more than 10 words)
_____________________________________________________________________
What did Leonard Poon worry about? (no more than 15 words)
______________________________________________________________________