题目

对于定义在R上的任意奇函数f(x)都有（    ）A.f(x)-f(-x)＞0        B.f(x)-f(-x)≤0        C.f(x)·f(-x)≤0       D.f(x)·f(-x)＞0 答案：解析：当x≠0时，f(x)·f(-x)＜0;当x=0时，f(x)·f(-x)=0,故f(x)·f(-x)≤0.答案：CHe tried to go away without being noticed by his employer but luck ___ him. 　 A. went with　　 B. went against　 C. went over　　 D. went along