...a*b)*c≠a*(b*c)2.For all integers a and b,there exist...
是英文的.在离散数学的课本里.还有关于such that 的否是什么啊.1.There exist a,b and c such that (a*b)*c≠a*(b*c)2.For all integers a and b,there exist integers q and r such that b=qa+r3.if n is an integer,n/(n+1) is not an intege