B
Astronauts are people who go out into space. Being an astronaut is an exciting job. While in space, astronauts can look down and see ___4___（cloud）, land, and water. They can even see the moon up close. Astronauts get the chance ___5___(see) more stars than you or I have ever seen. Being an astronaut may be exciting, ___6___ it is not an easy job. A person who ___7___(want) to be an astronaut has to study for years. There are many things an astronaut must learn to do before going into space.
【答案】4. clouds
5. to see 6. but
7. wants
【解析】
这是一篇记叙文。文章介绍了宇航员在太空中见到的景象，宇航员工作的特点等相关信息。
【4题详解】
考查名词。该空作see的宾语，应用名词，且空中的云彩不止一朵，故应用名词复数形式。故填clouds。
【5题详解】
考查非谓语动词。the chance后常接动词不定式作定语，故填to see。
【6题详解】
考查连词。前句句意：当宇航员可能是令人兴奋的。空后句意：当宇航员不容易。前后两句之间是转折关系，故填连词but。
【7题详解】
考查主谓一致。who ___4___(want) to be an astronaut是定语从句，修饰a person，引导词在从句中作主语，根据主谓一致原则，谓语动词应用第三人称单数形式，故填wants。
