内存限制：64 MB
时间限制：3.000 S
标准输入输出
题目类型：传统
评测方式：文本比较
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提交：8
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N numbers, randomly generated between [0; 1]
Make M operation, 1/2 probability to delete the maximum value, 1/2 probability to delete the minimum value
Calculate the sum of expected value module 109 + 7
Each test contains multiple test cases. The first line contains the number of test cases T(1 <= T <= 10000).
Description of the test cases follows.
The first line of each test case contains two integers n, m
1 <= m <= n <= 109
For each test case, print one integer - the answer to the problem.