Paragraph TwoAccidents and illnesses are unhappy things to talk about, but no one can expect to live a lifetime without having some kind of accident or becoming ill. Some accidents and illnesses are serious and may result in long periods of recovery from poor health.Accidents and illnesses are u_____.
【正确答案】：usual
【题目解析】：usual：常见的，普通的。本段讲的是事故与疾病是常见的现象。
