阅读理解。 Memory, they say, is a matter of practice and exercise. If you have the wish and really make a conscious effort, then you can quite easily improve your ability to remember things. But even if you are successful, there are times when your memory seems to play tricks on you. Sometimes you remember things that really did not happen. One morning last week, for example, I got up and found that I had left the front door unlocked all night, yet I clearly remember locking it carefully the night before. Memory 'tricks' work the other way as well. Once in a while you remember not doing something and then find out that you did. One day last month, for example, I was sitting in a barbershop waiting for my turn to get a haircut, and suddenly I realized that I had got a haircut two days before at the barbershop across the street from my office. We always seem to find something funny and amusing in incidents caused by people's forgetfulness or absent-mindedness. Stories about absent-minded professors have been told for years, and we never get tired of hearing new ones. Unfortunately, however, absent-mindedness is not always funny. There are times when 'tricks' of our memory can cause us great trouble. 1. If you want to have a good memory, you should ______. A. force yourself to remember things B. make a conscious effort of practice and exercise C. never stop learning D. try hard to remember things 2. Which of the following statements is TRUE according to the passage? A. One night the writer forgot to lock the front door. B. One night the writer forgot having locked the front door. C. The writer remembered to lock the door. D. The writer remembered unlocking the front door. 3. What can we infer from the last paragraph? A. Absent-mindedness stories can bring people fun. B. Absent-mindedness is more troublesome than forgetfulness. C. Absent-minded professors are often amused by the incidents, too. D. Absent-mindedness happens not only to professors but to all other people. 4. Which of the following could be the best title for this passage? A. The Key to a Good Memory B. 'Tricks' of Memory C. The Dangers of Forgetfulness D. The Dangers of Absent-mindedness