44. A. leave                  B. use                    C. find                 D. give

43. A. but                   B. and                   C. however             D. or

42. A. lived on                B. landed on               C. studied               D. written

41. A. blow                  B. look                   C. mix                D. fly

40. A. red                   B. black                  C. white                D. yellow

39. A. seen                   B. wrote                  C. heard                D. visited

38. A. hotter                  B. colder                  C. bigger               D. smaller

37. A. sound                 B. life                    C. air                  D. water

36. A. when                 B. what                  C. which               D. how

35. I got up late before, But now I         up early.

A. used to get                                       B. amused to get

C. amused to getting                                   D. used to getting

Maybe you know a lot about the city you live in. You may even know some interesting facts about Earth, but  36  do you know about Mars? Will there be   37  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  38   than Earth because it's farther from the sun. It's also the only planet whose surface can be  39   from Earth.

Mars is often called "the red planet" because the rocks on it have a dark   40   color. There are strong winds on Mars that can  41  dust into the hills.

For many years, people have   42  Mars. They have sent instruments and robots there. Some of the robots got there,   43  most failed.

NASA(美国国家宇航局) sent two robots to Mars two years ago. They wanted to  44   signs of water and life on Mars. Some day, humans will travel to Mars and have an even  45  look at our red neighbor. Maybe it could be you!