题目

On the third floor there are two rooms, _____ is used as a meeting-room.A.one of them B.the larger of whichC.and a larger of of them D.the largest one of which   答案：B若函数y=f（x）对任意的x，y∈R，恒有f（x+y）=f（x）+f（y），当x＞0时，恒有f（x）＜0（1）判断f（x）的奇偶性并证明；               （2）判断函数f（x）的单调性并证明；（3）若f（2）=1，解不等式f（-x2）+2f（x）+4＜0．