People often say that a dog is man's best friend. Over thousands of years, man has taught his dogs to do many kinds of work besides on light switches, open refrigerator doors and dial the telephone for their disabled owners. For the majority of people, however, dogs are simply pets and friends for both young and old members of the family.Dogs have been used to aid disabled people for centuries. A guide dog can lead its blind owner. Nowadays, dogs can be taught to turn guarding the home. For example, sheepdogs are famous for their ability to control a flock of hundreds of sheep.
guard 看守，看护 sheepdog 牧羊犬 flock 群 aid 帮助
disabled 残疾人 century 世纪 guide dog 导盲犬 dial 拨 majority 大多数