将左边和右边的句子连成对话。

①Do you like giraffes?____      A. It's a snake.

②What's that?____           B. I hear tigers.

③What colour are the pandas?____ C. No, I don't.

④What do you hear? ____    D. They're black and white.

设函数f(x)=lnx,g(x)=ax+$\frac{b}{x}$，它们的图象在x轴上的公共点处有公切线，则当x>1时，f(x)与g(x)的大小关系是（ ）