A．It is cheaper to travel by train than by plane.
B．The railway station is usually at the center of a city.
C．When you get off the plane you will find yourself right in the city center.
D．No motorcar or plane can carry as many goods as a train does.

A．It is a small amount to pay for so much precious metal.
B．It is difficult to judge the value of such an object.
C．It is reasonable for an object with such an important function.
D．It is too high for such a light weight.