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Humans have been trying to explore and inhabit（定居）Mars.One of the many difficulties is the lack of oxygen on the red planet.Luckily，NASA's Perseverance Rover（漫游者）can help.
Using an instrument called MOXIE，the rover successfully took carbon dioxide（二氧化碳）from the Mar's atmosphere and turned it into oxygen.NASA has said it plans to conduct more MOXIE tests.
MOXIE ran its first test for around an hour，producing just 6 grams（克）of oxygen.That's enough to keep an astronaut going for about 10 minutes.It seems that it can be improved.It won't keep someone alive for long，but it's a key step forward in exploring Mars.
Not only could that oxygen be used to allow people to breathe，but it would also lighten the load for return missions to Earth，or for trips to other parts of the solar system.Rockets need oxygen to burn fuel during liftoff（起飛）.Since we are now able to create oxygen on Mars，spacecraft can bring less of
it from Earth，significantly cutting down their weight.Less weight means less overall fuel（燃料）needed to launch rockets.
Oxygen is the heavier part of rocket fuel.If NASA wanted to get four astronauts off Mars，the spacecraft would need 27.5 tons of oxygen to do it.Keeping those four breathing for a year would require about one ton.At the rate MOXIE is going，producing 27.5 tons would take more than 475 years.But future devices could be larger and more efficient than the 18-Kg MOXIE.One day，we will come up with a bigger plan for humans when we finally send them there to make enough oxygen.
（1）What can MOXIE do？
D
D
A．Conduct tests on Mars.
B．Help send oxygen to Mars.
C．Find new places for humans.
D．Turn carbon dioxide into oxygen.
（2）What needs to be improved in the MOXIE tests？
D
D
A．Using less fuel to launch rockets.
B．Sending more astronauts to space.
C．Cutting down the weight of rockets.
D．Producing enough oxygen for the mission.
（3）What's the meaning of the word"it" in paragraph 4？
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D
A．MOXIE.
B．Carbon dioxide.
C．Rocket.
D．Oxygen.
（4）Which of the following is NOT TRUE according to the passage？
C
C
A．People want to live on Mars.
B．Four astronauts breathe about I ton of oxygen a year.
C．The device MOXIE is heavier than four astronauts.
D．A man uses about 6 grams of oxygen for breathing in 10 minutes.
