018.
I remember that when I was in my teens, I used to disobey many rules my parents told me. For example, when I kept on playing jazz records on the record player, my father used to criticize such music as noise and replace them with disks of classical music that I always considered extremely dull.
My parents were also very particular about the friends I went out with, always warning me that "one rotten apple could ruin a whole basket of apples." When I wanted to sleep with my pet dog Peppy, they immediately said NO because they thought that I would be bitten by fleas.
Today, however, I am also the father of a boy of fifteen, and I find that I, too, am pressuring my son with a lot of rules that he seems to find hard to follow. The other day, I noticed that my son's hair was too long, so I told him to have it cut short. Ordinarily, he is fairly obedient, but this time he put his foot down.
"What's wrong with long hair?" he said, "All my friends have long hair. And besides, it's my own hair, isn't it? I don't think you have the right to order me to cut it short, even if you're my father!"
When I was a boy, if I had spoken like this to my father, I know that he would have given me a good beating. But I suddenly realized that we are now living in a more liberal world, and that my son's wearing his hair long was merely an example of the generation gap that existed between us. So I gave in, and so he still wears his hair long.

答案解析：
(1) 正確答案為C。根據classical music that I always considered extremely dull. 我認為古典音樂非常無聊。可知，作者認為古典音樂很無聊，因此C項正確。
(2) 正確答案為A。根據My parents were also very particular about the friends我父母對我的朋友也很挑剔，可知，作者的父母對他說“一顆老鼠屎壞了一鍋粥”是怕兒子的朋友對他有不好的影響，因此A項正確。
(3) 正確答案為C。根據he put his foot down. put one's foot down的意思是拿定主意阻止；執意反對；可知，當作者要求他的兒子把頭發剪短時，遭到了兒子的堅決反對，因此C項正確。
(4) 正確答案為B。根據an example of the generation gap that existed between us這就是我們之間存在代溝的例證。可知，最適合這篇文章的標題為代溝，因此B項正確。