E

       Could we "terraform" Mars —that is, change its frozen, thin-aired surface into something more friendly and Earthlike? Should we? The first question has a clear answer: Yes, we probably could．Spacecraft, including the ones now exploring Mars, have found evidence that it was warm in its youth, with rivers flowing into vast seas．And right here on Earth, we've learned how to warm a planet: just add greenhouse gases to its atmosphere．Much of the CO₂ that once warmed Mars is probably still there, in frozen dirt and polar ice caps, and so is the water．

       Most of the work in terraforming, says NASA scientist Chris Mackay, would be done by life itself． "You don't build Mars," Mackay says．"You just warm it up and throw some seeds．" Powerful greenhouse gases could be produced from elements in dirt and air on Mars and blown into the atmosphere; by warming the planet, they would release the frozen CO₂, which would quicken the warming and increase atmospheric pressure to the point where liquid water could flow．Meanwhile, says botanist James Graham of the University of Wisconsin, human settlers could seed the red rock with a succession （系列） of ecosystems ?first bacteria and lichens （地衣）, which survive in Antarctica, later mosses （苔藓）, and after one thousand years or so, redwoods．Getting breathable oxygen levels out of those forests, though, could take thousands of years．

       However, Mars is in no immediate danger．Some space scientists recently recommended going to the moon or an asteroid （小行星） first, and pointed out the space agency lacks the funds to go anywhere．It didn't estimate the cost of gardening a dead planet．

72．What is the most essential to make Mars fit for living?

       A．Turn ice into flowing water．           B．Clean the dirty atmosphere．

       C．Make the atmosphere more suitable．    D．Go to the moon or an asteroid first．

73．What does the author think of the idea ofterraforming Mars?

       A．We could do it．        B．We couldn't do it．

       C．We should do it．       D．We shouldn't do it．

74．In the botanist's opinion, man needs to __________.

       A．enable Mars to clean its atmosphere

       B．build a greenhouse on Mars

       C．send some people to settle on Mars

       D．cultivate ecosystems from lower to higher life form

75．What is the best title for the passage?

       A．Making Mars the New Earth．     B．A Good Way to Change the Universe

       C．Humans' Great Power．        D．Terrible Science and Technology．

Astronauts aboard the space station celebrated a space first on Wednesday by drinking water that had been recycled from their urine(尿), sweat and water got from air. They said "cheers," clicked drinking bags and toasted NASA workers on the ground.
The urine recycling system is needed for astronaut stations on the moon and Mars. It also will have NASA money because it won’t have to ship up as much water to the station by space shuttles or cargo rockets. Besides, it’s important as the space station is about to expand from three people living on board to six.
The recycling system had been brought up to the space station last November by space shuttles Endeavour, but it couldn’t be used until samples(样品) were tested back on earth. So when it came time to actually drink up, NASA made a big deal of it. The three-man crew stood holding their drinks and congratulated engineers in two NASA centres that worked on the system.
“This is something that had been the stuff of science fiction,” American astronaut Michael Barratt said before taking a small mouthful. “The taste is worth trying.”
The new system takes the combined urine of the crew from the toilet, moves it to a big tank, where the water is boiled off, and the vapor(水蒸气) is collected. The rest of the urine is thrown away. Then the water vapor is mixed with water from air, and then it goes through filters (过滤器). When six crew members are aboard it can make about six gallons from urine in about six hours.
“Some people may find the idea of drinking recycled urine distasteful, but it is also done on earth, but with a lot longer time between urine and the tap,” said Marybeth Edeen, the space station’s national lab manager.
The technology NASA developed for this system has already been used for quick water purification after the 2004 Asian tsunami.
【小题1】 According to the text, the recycling system is important because ___________.

E
Could we "terraform" Mars —that is, change its frozen, thin-aired surface into something more friendly and Earthlike? Should we? The first question has a clear answer: Yes, we probably could．Spacecraft, including the ones now exploring Mars, have found evidence that it was warm in its youth, with rivers flowing into vast seas．And right here on Earth, we've learned how to warm a planet: just add greenhouse gases to its atmosphere．Much of the CO₂ that once warmed Mars is probably still there, in frozen dirt and polar ice caps, and so is the water．
Most of the work in terraforming, says NASA scientist Chris Mackay, would be done by life itself． "You don't build Mars," Mackay says．"You just warm it up and throw some seeds．" Powerful greenhouse gases could be produced from elements in dirt and air on Mars and blown into the atmosphere; by warming the planet, they would release the frozen CO₂, which would quicken the warming and increase atmospheric pressure to the point where liquid water could flow．Meanwhile, says botanist James Graham of the University of Wisconsin, human settlers could seed the red rock with a succession （系列） of ecosystems ?first bacteria and lichens （地衣）, which survive in Antarctica, later mosses （苔藓）, and after one thousand years or so, redwoods．Getting breathable oxygen levels out of those forests, though, could take thousands of years．
However, Mars is in no immediate danger．Some space scientists recently recommended going to the moon or an asteroid （小行星） first, and pointed out the space agency lacks the funds to go anywhere．It didn't estimate the cost of gardening a dead planet．
72．What is the most essential to make Mars fit for living?
A．Turn ice into flowing water．          B．Clean the dirty atmosphere．
C．Make the atmosphere more suitable．    D．Go to the moon or an asteroid first．
73．What does the author think of the idea ofterraforming Mars?
A．We could do it．                            B．We couldn't do it．
C．We should do it．                           D．We shouldn't do it．
74．In the botanist's opinion, man needs to __________.
A．enable Mars to clean its atmosphere
B．build a greenhouse on Mars
C．send some people to settle on Mars
D．cultivate ecosystems from lower to higher life form
75．What is the best title for the passage?
A．Making Mars the New Earth．           B．A Good Way to Change the Universe
C．Humans' Great Power．                     D．Terrible Science and Technology．