单项选择题

Human memories are quite complicated beyond our imagination. We remember some things better than other things. For example, November 22, 1963 is etched (铭刻) into the minds of nearly every English-speaking person over 40. It was, of course, the day that President Kennedy was shot. The fact that so many people can remember that moment demonstrates what a world-shattering one it was. But in the long run, it may be that what it demonstrates about the workings of the human train is more important. After all, why should we remember what we were doing when we heard of the assassination We take it for granted that our memories work this way.
Some people have the ability to reproduce things perfectly through what is known as an eidetic memory. These are the people who can glance at a newspaper and retain a ’snapshot’ memory of it. This sort of memory is quite different from the imprint that most of us would make. Try closing your eyes and bringing to mind a scene you know well—the pattern of the wall-paper in your bedroom, say, and then try to describe it perfectly. Almost certainly you will find it impossible. But people with eidetic memories really can examine the pictures in their mind’s eye as if they were the real things.
Even the most forgetful of us can improve our memories. Mnemonics (记忆术) can be learned by anyone. For example, if you want to remember a list of things, you could create an imaginary street scene in your mind’s eye, then ’place’ the things you need to remember in various places along the street. It helps to make the objects visually striking. If one of the things you need to remember is, say, to take the car in for a service, you might ’place’ the car with its engine dismantled, in some thoroughly unlikely setting—hanging from a lamp-post perhaps. When you later stroll down your ’street’ looking for the things on your list, the suspended ear will not escape notice.
Why is it strange that so many people can remember what they were doing when President Kennedy was assassinated