单选题 《复合题被拆开情况》 People like to think that life was better in the past. The air was cleaner, the water was clearer, people【C1】________friendlier, life was safer and, certainly, it was【C2】________. But were the good old days【C3】________so good? Probably【C4】________. Many of today’s problems existed(存在) in the past,【C5】________ some problems in the past do not exist today. For example, many diseases (疾病) are【C6】________control now. It is safe to say that life has always had its problems.【C7】________existed in the past, they exist in the present and, certainly, they【C8】________exist in the future. But just remember; in the future, we can【C9】________at today’s life and talk【C10】________the good old days!《问题》：【C5】