阅读理解Dogs are friends of man.They work for us.

阅读理解Dogs are friends of man.They work for us.
Dogs are friends of man.They work for us.They hunt for us.They play with us.But once,all over the world,dogs were wild.
Thousands of years ago,man began to train the wild dogs .The strong dogs became working alone.They were trained to protect the heavy loads.Theylearnt to keep watching sheep and other animals.Wild dogs had other jobs,too.Some dogs were not strong.But they could help man hunt for games.Other dogs were the best animal pets.At first,there were over a few kinds of dogs.Today,there are more than 100 kinds.
1.From this passage,we know that_.
A.all the animals have the same ancestor.
B.all dogs are as wild as they were many years ago
C.man has helped change animals
D.animals never change
2.What jobs can dogs do?
A.Keep watching over sheep .B.Hunt with man.
C.Pull heavy loads.D.All of the above.
3.The main idea of the whole story is that _.
A.man and dogs have the same ancestor
B.all animals are too wild to be man's friends.
C.dogs and man have been friends for a long time
D.people like to keep foxes as pets because they are tamed