Memory, they say, is a matter of practice and exercise. If you have the wish and really make a self-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 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 remembered locking it carefully the night before.
Memory “trick” works 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 barber(理发师) shop waiting for my turn to get a haircut, and suddenly I realized that I had got a haircut two days before at the barber shop across the street from my office.
　　We always seem to find something funny in incidents（小事） caused by people’s forgetfulness or absent-mindedness(心不在焉). Stories about absent-minded professors have been told for years, and we never got tired of hearing new ones. Unfortunately, however, absent-mindedness is not always funny. There are times when “trick” of our memory can cause us great trouble. （words: 169）
If you want to have a good memory, ________.

A．you should force yourself to remember things

B．you should make a self-effort of practice and exercise

C．you should never stop learning

D．you should try hard to remember things

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.

From the sentence "We never get tired of hearing new ones", we can infer that______.

A．we enjoy hearing new stories about absent-mindedness of professors

B．we don’t want to know anything more about absent-mindedness of professors

C．we will never get rid of（摆脱） listening to new stories about absent-mindedness

D．absent-mindedness happens not only to professors but to many other people