When I study English, I like to put my dictionary _______ my reach so that I can refer to it when necessary. A. out of B. beyond C. within D. in 答案:C
下列命题:
(1)x≥3时,不等式x+≥a恒成立,则a≤
(2)f(x)是定义在R上的以3为周期的奇函数,且f(2)=0,在区间(0,6)内整数解的个数的最小值是5
(3)数列a,a=3,a=(nN),则a=-2
(4)函数f(x)=︱x-2ax+b︱一定是偶函数
正确的命题是________