问题
填空题
有4双不同的手套，从中任取4只，至少有两只是一双的不同取法共有 种.(用数字作答)
答案
54
解：根据题意，从4双即8只不同的手套中任取4只，有C84=70种不同的取法，
而取出的4只没有是一双即4双中各取1只的取法有2×2×2×2=16种；
则至少有两只是一双的不同取法有70-16=54种；
故答案为54
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有4双不同的手套，从中任取4只，至少有两只是一双的不同取法共有 种.(用数字作答)
54
解：根据题意，从4双即8只不同的手套中任取4只，有C84=70种不同的取法，
而取出的4只没有是一双即4双中各取1只的取法有2×2×2×2=16种；
则至少有两只是一双的不同取法有70-16=54种；
故答案为54
阅读下列短文，根据短文内容完成表格中所缺信息，每空一词. “USA? Britain? Which country is better to study in?” We often hear such discussions. As China open its door, it is a dream for many Chinese students to study abroad. They want to learn about the outside world. It’s true that studying abroad can help students develop themselves. Their foreign language skills will be improved and it may be easier to find jobs. But there are problems that should be considered. Language is the first. Students must spend a lot of time learning another language. Students must also learn to live without parents’ care and deal with all kinds of things they haven’t to do before, like looking after themselves. There are reports about Chineses students abroad running into an ocean of difficulties and giving up finally. When they have to take care of themselves, it is hard for students to study well. Finally, studying abroad brings a heavy burden to the family. For most Chinese parents, the cost of studying abroad is very high. But is it worth it? We know that there are many famous people who have achieved success through their hard work in China. Liu Xiang is a good example. Once an American teacher invited him there, but he refused. He kept training hard with his Chinese teacher. He surprised the world when he won a gold medal at the Athens Olympic Games. So when you winder which country is better to study in, think it again.
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