it, be, can't, book, Lily's
________________________________________________________.
must, sunny, tomorrow, be, it
________________________________________________________.
巨石阵的未解之谜
The stone ring at Stonehenge is a famous sight for tourists in Britain.
One thing we know 1. (exact) about Stonehenge is that it was completed 3500 years ago. Experts think that originally there were 30 stones, 2. only 17 remain standing.
One of the main 3. (fact)that we don't know about Stonehenge is why it was put there. Perhaps it might have been a place for 4. (watch) the stars and planets. And we also don't know how Stonehenge was 5. (build). Some of the stones came from 200 kilometers away and some of them w6. 40 tons. We quite wonder how the workers 7. (manage) to get these huge stones into an upright position at that time，but we think that workers must have used ropes to pull them u8. . But how did the stones get there in the9. (one) place? 10. answer may be told in the future.
They plan to go for a p________ this weekend if it is sunny.
We can ride bikes to work rather than driving to p________ the air pollution.
地球以外是否存在生命
Is there intelligent life on other planets? For years, scientists said “No” or “We don't know”. Although they thought so, today, this is changing. They, Seth Shostak and Alexandra Barnett, believe that there is intelligent life in somewhere in the universe.
Why do Shostak and Barnett think there is intelligent life on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old. This is too long for only one planet in the whole universe to have intelligent life. The second reason is size—the universe is huge. Our galaxy (星系), the Milky Way, has at least 100 billion stars. Some planets that circle these stars might be similar to Earth.
Until recently, it was difficult to search for signs of intelligent life in the universe. But now, powerful telescopes (望远镜) allow scientists to identify (辨认) many more small planets—the size of Mars or Earth—in other solar systems.
Have life beings from space already visited Earth? “Probably not，” says Shostak，“The distance between planets is too great. In_fact,_they_could_be_trying_to_communicate_with_us_now. But we may not have the right tools to reply to their messages. But within the next 20 years, we could make contact with other life forms in our universe.”
1题完成句子；2～3题简略回答问题；4题找出并写下第二段的主题句；5题将文中画线句子译成汉语。
1.Scientists Seth Shostak and Alexandra Barnett think there is _________ in the universe.
2.What are the two reasons that scientists think there is life existing in the universe?
________________________________________________
3.How do scientists search for signs of life in the universe?
____________________________________________________
4.____________________________________________________
5.____________________________________________________
