Do you like dogs? Do you know the following things about dogs? The first pet dog Dogs are meat-eating animals. They belonged to the family of wolves   a long time ago. About 15,000 years ago, people started keeping wolves for hunting  . Over the time, the wolves began to look like dogs and they became people's pets. What a dog looks like Dogs come in different sizes, colors and shapes, but they're the same in some ways. All kinds of dogs have a set of forty-two strong teeth for eating. They have sharp claws   at the end of their feet for digging up soil   and holding onto the ground when they walk. They have very good eyesight. They also have high ability   to hear and smell. How a dog grows A mother dog gives birth to one to twelve babies at a time. New-born baby dogs cannot see or hear until they are two weeks old. The mother dog gives the baby dogs milk. When they are four weeks old, they start eating soft food. When they're eight weeks, the baby dogs have very strong legs and they can go for long walks. How to read a dog's feelings Dogs act differently when they have different feelings. When a dog is angry, it opens its mouth and shows its teeth. When a dog is frightened, it lowers its ears and holds its tail   between its legs. A happy dog always wags   its tail. ,. (10) What does the passage mainly tell us?
Some facts about dogs. The history of dogs. Something interesting about dogs. Dogs are human beings' friends.