Steven drives a school bus, but his bus isn't the same as other school buses because there aren't any children on it. There are only dogs. Steven's bus takes dogs to school at 8:00 in the morning and brings them back home at 5:30 in the afternoon. Steven takes the dogs to a dog school. There he teaches the dogs to do many things: sit down, stand up, bring the shoes to the master, keep the master from danger  . Many dogs go to Steven's school--big dogs, small dogs, old dogs, young dogs. Steven says that young dogs can learn more quickly. Which kind of dogs is easy to teach?
Young dogs. Old dogs. Strong dogs . Big dogs.