根据下面内容，回答 68~71题：DIt’s not easy being a teenager(13至19岁青少年)-nor is it easy being the parent of a teenager．You can make your child feel angry, hurt or misunderstood by what you say without realizing it yourself．It is important to give your child the space he needs to grow while gently letting him know that you’11 still be there for him when he needs you．Expect a lot from your child，just not everything．Except for health and safety problems， such as drug use or careless driving，consider everything else open to discussion．If your child is unwilling to discuss something，don’t insist he tell you what’s on his mind．The more you insist， the more likely that he’11 clam up．Instead，let him attempt to solve(解决)things by himself. At the same time，remind him that you’re always there for him should he seek advice or help．Show respect for your teenager’s privacy(隐私)．Never read his mail or listen in on personal conversations．Teach your teenager that the family phone is for the whole family. If your child talks on the family’s telephone for too long，tell him he can talk for l5 minutes，but then he must stay off the phone for at least all equal period of time．This not only frees up the line so that other family members can make and receive calls，but teaches your teenager moderation(节制).Or if you are open to the idea，allow your teenager his own phone that he pays for with his own pocket money or a part-time job.第13题：The main purpose of the text is to tell parents__________.