2.Loyal： 忠诚的，忠心的; 忠贞的
3.Breed: 品种; 培育; 饲养;
4.Security: 安全; 保证，担保; 保护，
5.Limitless: 无限制的; 无界限的; 一望无际的; 无限期的
Dogs are people’s best friends. Whether they are as reliable workers, family pets or loyal companions, dogs are wonderful domestic animals that offer a number of qualities that are put into good use by humans.
1. In total there is said to be around 400 million dogs in the world. There are hundreds of different breeds of dogs.
2. Dogs perform many useful tasks for humans including hunting, farm work and security as well as assisting those with disabilities such as the blind.
3. Although experts often disagree, there is scientific evidence which shows that the domestication of dogs could have occurred more than 15,000 years ago.
4. The most popular breed of dog in the world is the Labrador. With their gentle nature, obedience, intelligence and near limitless energy, Labradors make for excellent family pets and reliable workers. They often assist police and are a common choice as guide dogs.
5. The average life span for a dog is around 10 to 14 years.