皮皮学，免费搜题
登录
搜题
【单选题】
在自然数集N上，下列运算不满足封闭性的是A.
a*b=a+2b
B.
a*b=a-b
C.
a*b=max(a，b)
D.
a*b=abs(a-b)
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】With ________ based CNC machine tool controllers, maintenance and repair are no longer an issue.
A.
PC
B.
PID
C.
FMS
D.
MT
【单选题】These questions are too difficult, they me.
A.
Utilized
B.
evolved
C.
guaranteed
D.
frustrated
【简答题】Paraphrase the following sentences. You may need to refer to the context in which they are used. These are questions which every individual asks himself at one time or another, sometimes calmly and me...
【单选题】These are questions ______ by history.
A.
left over
B.
left off
C.
leaving out
D.
leaving behind
【简答题】These are questions which every individual asks himself at one time or another, sometimes calmly and meditatively, sometimes in agonizing uncertainty or despair. (Para. 1)
【简答题】简述‘1’、“1”、1.0、1 四个常量的之间的区别 。
【简答题】When is it time to start thinking about a new job ?Is it acceptable to switch jobs to work with a close friend ?Can you leave an employer after the two-week training period is up ?Should you stick wit...
相关题目：