题目

完型填空。Young people are often unhappy when they are with their parents. They say that their parents don’t  1  them. They often think their parents are too strict with them, and they are never given a   2   hand.Parents often find   3   difficult to win their children’s trust and they seem to forget how they themselves   4   when they were young.For example, young people like to do things without much thinking. It is one of their ways to  5  that they grow up and they can do with any difficult things. Older people worry more easily. Most of them plan things ahead and　　体内的遗传信息如果发生改变，会对个体的某些方面产生影响而产生疾病，这种病叫_________。