My favourite teacher is our English teacher. She is a very beautiful woman. She is thirty-six years old. She has a round face, black hair, big eyes, a small nose and a small mouth. She is very kind to us. She often plays games with us. S
符号x表示不超过x的最大整数,例如π=3,-1.08=-2,定义函数x=x-x,给出下列四个命题:(1)函数x的定义域为R,值域为0,1;(2)方程x=12有无数个解;(3)函数x是周期函数;(4)函数x是增函数.其中正确命题的个数有( )
已知△ABC的面积为36,将△ABC沿BC的方向平移到△A′B′C的位置,使B′和C重合,连接AC′交A′C于D,则△C′DC的面积为( )