阅读下面材料，在空白处填入适当的内容(一个单词)或括号内单词的正确形式。答案写在答题卡上。
If you do not use your arm or your legs for some time, they become weak; when you start using them again, they   __ (slow) become strong again. Everybody knows that. Yet many people do not seem  __(know) that memory works in the same way. When someone says that he has a good memory, he really means that he keeps his memory in practice by using it.   __someone else says that his memory is poor, he really means that he does not give it enough chance to become strong. If a friend says that his arms and legs are weak, we know that __is his own fault(过错). But if he     __(tell) us that he has a poor memory, many of us think that his parents are to blame(受责备), and few of us know that it is just his own fault. Have you ever found that some people can’t read or write but usually they have     __(good) memories than others? This is     __they cannot read or write and they have to remember things; they cannot write down in       __little notebook. They have to remember days, names, songs and stories; so their memory is the whole time being     _ (exercise). So if you want to have a good memory, learn__the people; Practice remembering.