A refrigerator is used for keeping food fresh for a long period of time.
Fresh food is good.
A refrigerator keeps food good a long time.
What appliance can keep food good a long time?
[a] toaster
[b] Fuel cells
[c] Cooking
[d] a hydraulic system
[e] an electric stove
[f] oven
[g] refrigerator
[h] vacuum cleaner