A、A specialist in teenager studies. B、A parent with teenage children. C、A headmaster of a middle school. D、A doctor for mental h

Parents should stop blaming themselves because there’s not a lot they can do about it. I mean the teenager problem. Whatever you do or however you choose to deal with it, at certain times a wonderful, reasonable and helpful child will turn into a terrible animal.
    I’ve seen friends deal with it in all kinds of different ways. One strict mother insisted that her son, right from a child, should stand up whenever anyone entered the room, open doors and shake hands like a gentleman. I saw him last week when I called round. Sprawling himself on the sofa in full length, he made no attempt to turn off the loud TV he was watching as I walked in, and his greeting was no more than a quick glance at me. His mother was ashamed. "I don’t know what to do with him these days," she said. "He’s forgotten all the manners we taught him."
    He hasn’t forgotten them. He’s just decided that he’s not going to use them. She confessed that she would like to come up behind him and throw him down from the sofa onto the floor.
    Another good friend of mine let her two daughters climb all over the furniture, reach across the table, stare at me and say, "I don’t like your dress; it’s ugly." One of the daughters has recently been driven out of school. The other has left home.
    "Where did we go wrong?" her parents are now very sad. Probably nowhere much. At least, no more than the rest of that unfortunate race, parents. Questions 20 to 22 are based on the passage you have just heard.
20. Who is most probably the speaker?
21. What can we infer about the parents of the two daughters from the passage?
22. What is the speaker’s opinion about the sudden change in teenage children?