_____is a good form of exercise for both young and old.
A. The walk     B. Walking     C. To walk     D. Walk

_____ is a good form of exercise for both young and old.

A. Walk                   B. Walking

C. The walk               D. To walk

_____ is a good form of exercise for both young and old.

A. Walk　　　　　　　　　　 B. Walking

C. The walk　　　　　　　　 D. To walk

____ is a good form of exercise for both young and old.

A. Walk  B. Walking

C. The walk    D. To walk

_____ is a good form of exercise for both young and old.

A. Walk  B. Walking

C. The walk    D. To walk