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问题 选择题
定义一种运算“*”：对于自然数n满足以下运算性质：（1）1*1=1，（2）（n+1）*1=n*1+2，则n*1等于

A.n-1
B.2n-1
C.2n+1
D.n2
答案

答案：B

单项选择题

Jerome wrote each of the integers 1 through 20, inclusive, on a separate index card. He placed the cards in a box, then drew cards one at a time randomly from the box, without returning the cards he had already drawn to the box. In order to ensure that the sum of all the cards he drew was even, how many cards did Jerome have to draw ？（）

A.19

B.12

C.11

D.10

E.3
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填空题

诺思认为，制度的变迁和报酬的递增受到一系列主客观因素的制约，在这一系列的因素中，______在很大程度上决定了报酬的实现方式。
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