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Maybe you know a lot about the city you live in. You may even know some interesting facts about Earth, but 1 do you know about Mars? Will there be 2 there just like people on Earth? 　　Mars is the fourth planet from the sun and it's the most like Earth, but it's much 3 than Earth because it's farther from the sun. It's also the only planet whose surface can be 4 from Earth. 　　Mars is often called "the red planet" because the rocks on it have a dark 5 color. There are strong winds on Mars that can 6 dust into the hills. 　　For many years, people have 7 Mars, They have sent instruments and robots there. Some of the robots got there, 8 most failed. 　　NASA(美国国家宇航局) sent two robots to Mars two years ago. They wanted to 9 signs of water and life on Mars. Some day, humans will travel to Mars and have an even 10 look at our red neighbor.
( )1. A. when ( )2. A. sound ( )3. A. hotter ( )4. A. seen ( )5. A. red ( )6. A. blow ( )7. A. lived on ( )8. A. but ( )9. A. leave ( )10. A. faster	B. what B. life B. colder B. wrote B. black B. look B. landed on B. and B. use B. farther	C. which C. air C. bigger C. heard C. white C. mix C. studied C. however C. find C. closer	D. how D. water D. smaller D. visited D. yellow D. fly D. written D. or D. give D. lower