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[单选题]
在整数集上,下列运算能构成群的是( )
A
ab=max{a,b}
B
ab=|a-b|
C
ab=a+b+2
D
ab=ab
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参考答案
试题答案:
C
答案解释:
在C中,封闭性、可结合性显然,-2是其幺元,a的逆元是(-a-4)。
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