下列说法正确的是（　　）

A．具有相反意义的两个数互为相反数

B．符号不同的两个数互为相反数

C．相反数是本身的数是0

D．相反数不大于本身的数是正数

This vehicle bounces and glides along the ground ______.

A．at an average speed of 40 miles an hour

B．of 40 miles an hour at an average speed

C．at 40 miles an hour of an average speed

D．of an average speed at 40 miles an hour