阅读理解。 You are made of seventy-three percent water. You have 206 bones. There are more sweat glands (汗腺) in your feet than in any other part of your body. There are about sixty muscles in your face; you use twenty of them to smile but forty to frown (皱眉). Your heart beats over 100,000 times each day. You are really amazing! The human body is a complex machine. From the day we are born our bodies grow and change because of our environment, diet and habits. The body has many different organ (器官) systems and parts that work together to allow us to breathe, move, see, talk, and eat food all at the same time. Most of the time we are unaware (预兆) of what is happening in our bodies; usually it's only when we get sick or feel pain that we notice. Many people do not take enough care of their complex machines. Bad habits like smoking, drinking too much alcohol (酒精), and eating junk food damage our bodies. Stress can also cause health problems. People who worry a lot or have busy jobs often don't get enough sleep, or don't eat properly. We also damage our bodies by playing sports or having accidents. In 1999, Americans made more than 102,000,000 visits to emergency rooms. The two most common reasons were for injure (伤害) and poisoning. ER patients were also treated for many other medical problems-from bad cuts and broken bones to serious illness that needed surgery (外科手术). As with any machine, the better you take care of it, the longer it will last. Of course, the best way to take care of your amazing machine is to eat the right food, do regular exercise, and get enough sleep. Oh, and don't forget to smile! 1. What percentage of muscles in your face can be used to smile? [     ] A. A quarter. B. One-third. C. Three quarters. D. Two-thirds. 2. Some factors (因素) may cause health problems except . [     ] A. bad habits B. playing sports or having accidents C. stress D. performing surgery 3. What does the word 'damage' mean in Paragraph 3? [     ] A. 有益 B. 锻炼 C. 损害 D. 影响 4. Which of the following statements is Right according to the passage? [     ] A. It's reported that less than 70% of body is made up of water. B. A lot of people know the importance of looking after their bodies. C. We seldom notice what is happening in our bodies until we get sick. D. Injury and bad cuts are the most common reasons in America in 1999. 5. What can't you do if you want to keep fit? [     ] A. Eat the healthy food. B. Take exercise regularly. C. Get enough sleep. D. Don't smile often.