2012淘金英语专业四级听写 上海外国语大学 请从正文部分开始听写
Experts say earwax protects and cleans the ear. It traps dirt and other matter and keeps insects out. Doctors think it might also help protect against infections. And the waxy oil keeps ears from getting too dry. There are two kinds of earwax. Most people of European or African ancestry have the "wet" kind, while East Asians commonly have "dry" earwax. The glands in the ear canal that produce the wax make too much in some people. Earwax is normally expelled and it falls out of the ear or gets washed away. But extra wax can harden and form a blockage that interferes with sound waves and reduces hearing. People can also cause a blockage when they try to clean out their ears, but only push the wax deeper inside. Earwax removal is sometimes necessary. But you have to use a safe method or you could do a lot of damage.