题目

They are trying to make sure that 5G terminals ________ by 2022 for the Beijing Winter Olympics. A . will install B . will have been installed C . are installed D . have been installed 答案：B若函数y=f（x）的反函数y=-f-1（x）的图象与y轴交于点P（0，2），则方程f（x）=0的根是（ ）A．x=4B．x=3C．x=2D．x=1