题目

— Is that woman Ms. Zhang?— ________. She's my aunt. A . Yes, it is. B . Yes, she is. C . No, it isn't. D . No, she isn't. 答案：D函数f(x)=112x4-12ax2，若f（x）的导函数f′（x）在R上是增函数，则实数a的取值范围是（　　） A、a≤0B、a≥0C、a＜0D、a＞0