单选题 If you do not use your arms or your legs for 1 , they will become weak; and when you start using them again, they will gradually become strong again. Everybody 2 this, and nobody would think of 3 the fact.
Yet there are many people who seem 4 that the memory works in the same way. When someone says that he has a good memory, 5 really means that he 6 his memory 7 practice by exercising it very often, 8 consciously or unconsciously. When someone else says that his memory is 9 , he means that he does not give it enough chance 10 strong. The position is exactly the same as 11 of 12 people, one of whom exercises his arms and legs by playing balls, 13 the other sits in a chair or a car all day. If a friend of yours says that his arms are weak, we know that it is his own 14 . But if he tells us that he has a poor memory, many of us think that his parents are 15 , or that he is just 16 , and few of us realize that it is just 17 it was his arms or legs that were weak. Not all of us can become very strong in body or very clever 18 mind, but all of us can improve our strength and our memory by the same method.
Have you ever noticed that people who cannot read or write usually have 19 memories than those who can? Why is this? Of course, because they cannot write down something in a little notebook or something else. They have to remember names, places, songs and stories; so their memory is always 20 .