The market for used computers is getting larger and larger as the years ________．

1. A.
   get on
2. B.
   run on
3. C.
   push on
4. D.
   go on

The market for used computers is getting larger and larger as the years 　　　　　.

　 A．put on　　　 B．go on　　　 C．run on　　　 D．push on