My sister asked me to go there by train, because the train ticket is ______ the plane ticket.  [ ]

A. as cheap three times as            

B. as three times cheap as  

C. three times cheaper than          

D. cheaper three times than

关心爱护残疾人是每个公民应具备的美德，为了方便盲人行走，现在许多城市公路上铺设有凹凸刻纹的盲道。如图所示，人走在盲道上，         ____减小，在压力一定时，脚底受到的         _____增大，从而盲人通过脚底能感觉出来，因此不用盲杖也能在盲道像正常人行走。