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C
Most people, when they travel to space, would like to stay in orbit for a few days or more. And this stands to reason, if you’re paying $20,000 for your trip to orbit! So in order for tourism to reach its full potential there’s going to be a need for orbital accommodation — or space hotels. What would a space hotel actually be like to visit? Hotels in orbit will offer the services you expect from a hotel —private rooms, meals, bars. But they’ll also offer two unique experiences: impressive views — of Earth and space — and the endless entertainment of living in zero gravity — including sports and other activities that make use of this.
The hotels themselves will vary greatly — from being quite simple in the early days to huge luxury structures at a later date. It’s actually surprising that as late as 1997, very few designs for space hotels were published. This is mainly because those who might be expected to design them haven’t expected launch costs to come down far enough to make them possible.
Lots of people who’ve been to space have described vividly what it’s like to live in zero gravity. There are obviously all sorts of possibilities for dancing, gymnastics, and zero-G sports. Luckily, you don’t need to sleep much living in zero gravity, so you’ll have plenty of time for relaxing by hanging out in a bar with a window looking down at the turning Earth below.
Of course all good things have come to an end, unfortunately. And so after a few days you’ll find yourself heading back though you’ll be much more expert at exercising in zero gravity than you were when you arrived. You’ll be thinking how soon you can save up enough to get back up again — or maybe you should change jobs to get to work in an orbiting hotel.
39. When traveling in space, most people would like to stay in orbit for a few days because _____. 
A. it is expensive to travel in space
B. they would find the possible life in other star systems
C. they could enjoy the luxury of space hotels
D. they want to realize the full potential of tourism
40. Which of the following is a unique experience that space hotels will offer?
A. The gravitational pull.     B. The special views.
C. The relaxation in a bar.    D. The space walk.
41. Which of the following is NOT discussed in the passage?
A. When was the space traveling made possible?
B. What are the unique experiences that space hotels will offer?
C. Why were there not many published designs for space hotels?
D. How can the travelers enjoy themselves in space hotels?
42. This passage is mainly about ________.
A. traveling in space
B. the ways of living in space hotels
C. zero gravity and space hotels
D. the description of space hotels
D
US researchers have found traces of an ancient lake on Mars recently, increasing hopes of discovering evidence that billions of years ago the Red planet hosted life.
The lake, which dates back some 3.4 billion years, appears to have covered as much as 80 square miles and was up to 1,500 feet deep, said the team from the University of Colorado.
"This is the first clear evidence of shorelines on the surface of Mars," said Boulder's research associate, Gaetano Di Achille, in a study published in the latest edition of Geophysical Research Letters.
"The identification of the shorelines and accompanying geological evidence allows us to calculate the size and volume of the lake, which appears to have formed about 3.4 billion years ago."
Analysis of the images has shown the water carved out the canyon (溪谷) in which it was found, which then opened out into a valley depositing (使淤积) sediment (沉积) which formed a delta (三角洲).
"Finding shorelines is a great discovery to us," said assistant professor Brian Hynek, adding it showed the lake existed at a time when Mars was thought to have been cold and dry.
Scientists believe the oldest surfaces on Mars formed during the wet and warm era known as the Noachan epoch, about 4.1 billion to 3.7 billion years ago. 
The newly discovered lake is believed to date from the Hesperian era and postdates the end of the warm and wet period on Mars by 300 million years, according to the study.
Scientists believe deltas next to the lake may well hold secrets about past life on Mars as such places on Earth have become the natural deposits of organic carbon and other markers of life.
43. The size of the lake found on Mars is ______.
A. 80 square miles       B. 1,500 square miles 
C. 3.4 billion square miles      D. 300 million square miles
44. When the lake existed, the weather on Mars was ____. 
A. hot and wet   B. wet and warm   C. cold and dry  D. cold and wet
45. Why do scientists think deltas near the lake may hold secrets about past life on Mars?
A. Because similar places on Earth have become natural deposits of markers of life. 
B. Because someone has put secrets about past life on Mars there. 
C. Because past life has been found in other deltas on Mars. 
D. Because some people are said to have already seen life marks there.
46. Which of the following statements is NOT true according to the passage? 
A. The Noachan epoch was a wet and warm era.
B. The lake might have existed 3.4 billion years.
C. The discovery can’t fully prove that the Mars once hosted life.
D. The lake traces prove that there exists life on Mars now.
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