单项选择题

‎设，A上的二元运算*定义为：，则在代数结构中，幺元是( )，零元是( )。(注：答案之间用英文逗号,分开)‏

你可能感兴趣的试题

the Mississippi, along with its six tributaries drain more than half of all U. S. states, stretching from the Rocky Mountains in the west to the Appalachian Mountains in the east and to the Canadian border on the north and includes most of the Great Plains.

答案：正确

单项选择题

排在导致运动损伤原因的第一位的是什么？

A.技术动作不合理

B.心理素质不好

C.过度疲劳