题目

We must do something to stop people from ______.     A. to throw litter about    B. to throw litter into     C. throwing litter about    D. throwing litter into 答案：C函数f（x）=1+log2x与g（x）=2-x+1在同一直角坐标系下的图象大致是（ ）A．B．C．D．