the function F(x)=cube root of (x/(1+x)) is a composite function of "fog". the f and g are respectively : a. x/(1+x), cube root of x, b. cube root of x, x/(1+x), c. cube root of x/(1+x), , cube root of x, d. none of them 我选的答案是B。 但是不知道如何写出解题步骤, 请各位达人明示! 谢谢