2011 AMC 8 第 24 题
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所有题目均经美国数学协会（MAA）官方合法授权使用。
24.
可以用多少种方式写成两个质数之和？
In how many ways can be written as the sum of two primes?
小提示：
检查 是否为质数
Check whether is prime.
大提示：
两个质数之和为奇数时，必须包含唯一的偶质数
An odd sum of two primes must include the only even prime.
解答：
两个数相加得到奇数时，一个必须是奇数，另一个必须是偶数。唯一的偶质数是 ，所以另一个数只能是 。但 不是质数，因此 不能写成两个质数之和。
所以正确答案是 A。
For two numbers to add to an odd number, one of them must be odd and the other even. Thus the only even prime is so the other number is forced to be is not prime, however, so cannot be written as the sum of two primes.
Thus, A is the correct answer.
其他年份的第 24 题
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- 1989 AMC 8
- 1990 AMC 8
- 1991 AMC 8
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