away.

　　D．Because in a space station, there aren't enough places for astronauts to store their things.

　　解析：选B　推理判断题。根据第二段的第二句"They spend the night floating in a sleeping bag inside a small cubicle (小隔间) on the ceiling"和第三段的第二句"Can you imagine the mess that running water would make in zero gravity"以及第五段的最后一句"Almost every task is carefully planned by mission control - although most astronauts spend their first days losing things until they get used to sticking everything they use to the walls with Velcro, duct tape (强力胶带) or clips (夹子)"可知，在失重状态下没有被固定的东西会飘浮起来以至于会丢失，故选B。

　　3．What parts become weak if astronauts don't exercise?

　　A．Their teeth and bones.

　　B．Their brains and bones.

　　C．Their teeth and muscles.

　　D．Their bones and muscles.

　　解析：选D　细节理解题。根据第四段第二句中的"The lack of gravity makes bones more fragile and muscles lose strength"可知，宇航员不锻炼的话，他们的肌肉和骨头会变得虚弱。

　　4．What is the best title for the text?

　　A．The Problems We Met in Space

　　B．How to Become an Astronaut

　　C．Living and Working in Space

　　D．The International Space Station

　　解析：选C　标题归纳题。根据第一段和全文的整体内容可推知，本文主要讲的是太空中宇航员的生活和工作情况，故选C。

　　Ⅱ.阅读七选五

　　6 Tips for Healthy, White Teeth

　　·Go on a white­teeth diet. If you're quaffing (畅饮) red wine and black tea, or smoking cigarettes, expect the results to show up as not­so­pearly whites.

　　·Throw away your toothbrush or electric toothbrush head every two to three months.__1__ According to dentist Harold Katz, the best way to brush is by placing your toothbrush at a 45­degree angle against your gums (牙龈) and gently moving it in a circular motion. Grip the toothbrush like a pencil so you won't scrub (刷洗) too hard.

　　·Use a tongue scraper (刮刀) every morning to remove tongue plaque (舌斑) and freshen breath. One cause of bad breath is the build­up of bacteria on the tongue, which a daily tongue scraping will help banish (消除). __2__

　　·Eat "detergent (清洁剂)" foods that are firm or crisp to help clean teeth as you munch (咀嚼)．__3__ For best results, make "detergent" foods the final food you eat in your meal if you know you won't be able to brush your teeth after eating.

　　·Stay fresh. Check by licking (舔) your palm and smelling it while it's wet. If you smell something, it's time for a sugar­free breath mint (薄荷). Shopping for mouthwash? __4__ Mouthwashes with too much alcohol can dry out mouth tissue, making it more prone (易于) to bacteria.

·Brushing your teeth first and last are the two most crucial times of the day, as