四、閱讀測驗【請依照段落上下文意，選出最適當的答案】        The human body is a complex machine. From the day we are born, our bodies grow and change in responseto our environment, diet, and habits. The body has many different organ systems and parts that work together toallow us to breathe, move, see, talk, and digest food all at the same time. Most of the time we are unaware ofwhat is happening in our bodies； usually it is only when we get sick or feel pain that we notice.        Many people do not take care of their complex machines. Bad habits like smoking, drinking too muchalcohol, and eating junk food damage our bodies. Stress can also cause health problems. People who worry a lotor have busy jobs often don’t get enough sleep or don’t eat properly. We can also damage our bodies when weplay sports or get into accidents. Studies done by the Australian government show that most people get hurtbecause of an accidental slip or fall or because of injuries from car accidents. It’s true that a lot of people go tothe hospital because of serious illnesses, but far more people end up there because they simply weren’t beingcareful.       Like machines, different body parts sometimes wear down from old age. People over the age of 65 are morelikely to fall and hurt themselves, and these injuries—from bad cuts to broken bone—usually require seriousmedical attention. There are many treatments available to help older people recover from illness and injury. It isnow common for older people with damaged joints, for example, to have surgery to replace the old joint with anew one made of plastic or metal. Instead of suffering aches and pains through their retirement days, older peopleare able to lead happier and more comfortable lives.        The best way to take care of your amazing machine is to eat the right foods, do regular exercise, and getenough sleep. Oh, and don’t forget to smile!
【題組】31. What is this reading passage mainly about?
(A) how age and lifestyle affect the amazing human body
(B) how elderly people are living longer and longer
(C) how our bodies change and damage from birth
(D) how busy people eat poorer and sleep less