两个数相乘一个因数扩大3倍，积若不变，另一个因数应______．
两个数相乘，一个因数扩大3倍，积若不变，另一个因数应缩小3倍；
如：2×18=36，
一个因数2扩大3倍变成6，要使积36不变，另一个因数就得是：36÷6=6，
另一个因数由18变成6，是除以3，即缩小3倍，
所以进一步说明两个数相乘，一个因数扩大3倍，积若不变，另一个因数应缩小3倍．
故答案为：缩小3倍．
| 阅读下列短文，从文后各题所给四个选项中选出一个最佳答案。 | ||||
| There was a blind girl who hated herself because she wasn't able to see anything. In fact, she __1__ nobody except her boyfriend, for he was always __2__ to help her. She often told her boyfriend, "If I could see the __3__, I would marry you." One day, someone donated a pair of __4__ to her. When the bandages (绷带) came off, she was able to see everything, including her boyfriend, for the __5__ time. He asked her, "Now that you could see everything, will you __6__ me?" The girl looked at her boyfriend and was greatly surprised to see that he was __7__. She had never hoped that. She wouldn't like to be with a blind husband for the rest of her life, so she __8__ to marry him. Her boyfriend left in tears and a few days later wrote a __9__ to her, saying, " My dear, take good care of your eyes. __10__ they are yours, they were mine." This is how the human brain (人脑) often works when our status (地位) changes. Only a very few remember what __11__ was like before. And we often ask for more than we need. Life is a gift. Today, before you complain (抱怨) about __12__ of your food, think of someone who has nothing to __13__. Before you complain about your old __14__, think of the people who are living in the streets. And when you are tired and complain about your job, think of those who have no jobs. So __15__ what you have and don't forget your past. | ||||
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