题目内容：

（广东省深圳市耀华实验学校2018届九年级上学期期中）People often say that a dog is 1. (man) best friend. Over 2. (thousand) of years, man has 3. (teach) his dogs to do many kinds of work besides 4. (guard) the home. For example, sheepdogs are famous 5. their ability to control a flock of hundreds of sheep.

Dogs have been used to aid 6. (able) people for centuries. A guide dog can lead its blind 7. (own). Nowadays, dogs can be taught 8. (turn) on light switches, open refrigerator doors and dial the telephone for their disabled owners. For the majority of people, 9., dogs are 10. (simple) pets and friends for both young and old members of the family.