单选题 Memory is the ability to keep track of things that have happened in the past. Memory really is learning. One needs memory to ride a bicycle. A dog needs to remember if it is to come when called.
Memory is said to be stored in the brain as a 'memory trace (记忆痕) '. What makes up this trace is not known. Some scientists believe that certain chemical substances may carry certain memories. For example, one substance, when given to rats, causes them to fear the dark.
Other research into memory has to do with how the brain works. Psychologists use three means to find out bow a person remembers. For example, give a person a grocery list. Let the person memorize the list, then put it away. The most natural way to find out how much a person remembers of the grocery list is to ask what he or she remembers. This is called the method of recall. Another method is called recognition. Give the person another grocery list. Ask him or her to choose items on the first list from the items that are on only the second list. Often a person will be able to recognize things that he or she cannot recall. A third method of finding how much a person remembers is called relearning. Here the person is asked to read over the first list. The person will probably learn the list the second time faster than he did the first time. The difference in the time it takes to relearn the list is thought of as measure of how much a person has remembered.
One way of remembering something is to repeat it many times. Interest is very important. Boring lists of facts are much more difficult to remember than something that we understand and are interested in. Motivation, or wanting to do something, is also important. Motivation is linked with reward. For example, a hungry animal quickly learns how to do something if that action gets the animal food. In humans, wanting to learn is often motivation. The praise of a teacher or the knowledge that an answer is correct is rewarding.

单选题 We can learn from the 2nd paragraph that ______.

【正确答案】 B

【答案解析】第二段。文章说，人们还不知道这个痕迹是由什么构成的。虽然文章紧接着说有些科学家believe(认为)如何。但believe这个词显示了不肯定的含义。It is hard to tell很难说，也表示了不肯定。选项A，给老鼠某种物质可使它害怕黑暗，而不是不好的记忆会使它害怕黑暗。选项C，某些化学物质会导致某些记忆，但不是所有的化学物质都会导致某些记忆；而这并不是此段的中心内容。选项D，存在大脑中的记忆实际上是一种记忆痕，而不是一种物质。

单选题 The way to pick out the items on the first list from the second is known as ______.

【正确答案】 A

【答案解析】第三段。三种方法检验大脑是如何工作的。第一种，给受试者一张购物单，让他记，然后看他能记多少。这种办法叫回忆(recall)。第二种，给受试者另一张购物单，让他在第二章购物单中找出曾在第一张购物单中出现的物品。这个办法叫识别(recognition)。第三种办法是让受试者反复记第一张购物单，第二遍比第一遍的速度要快。这个办法叫重复记忆(relearning)。