Nowadays many people like to have dogs as their pets. Dogs are friends of man not only because they are lovely but also because they are faithful to their masters.

现在许多人都把狗当作他们的宠物。狗是人类的朋友，不仅因为它们可爱，而且因为它们对主人忠诚。

Dogs can do a lot of work for man. They play with us. They hunt with us. They keep door for us. But long ago, dogs all over the world were wild.

狗能为人类做很多工作。它们可以和我们玩，它们可以跟我们一起打猎，它们可以给我们看家。但是以前世界上的狗都是野生的。

Dogs can date back to the Stone Age. All dogs have the same ancestor. It is believed that their ancestor was much like a wolf. Other animals, such as the fox, came from this ancestor, too. Hundreds of thousands of years ago, man began to tame wild dogs. After the dogs were tamed, they were trained. The strong dogs became working animals. They were trained to pull heavy loads. They learned to keep an eye on the sheep and other animals. Working dogs had other jobs, too.

狗可以追溯到石器时代。所有的狗都是同一个祖先，人们相信狗的祖先很像狼。其他动物，如狐狸，也是来自这个祖先。几千年前人类就开始驯服野狗，狗被驯服后，人们就训练它们。强壮的狗成为人类工作的帮手，人们训练它们拉重的货物。它们学会了帮人们照看绵羊和其它的动物。

Some dogs were not strong. But they could help man hunt for game. Other dogs were best as pets.

有些狗不够强壮，但它们能帮人们寻找猎物。还有些狗成了人们的宠物。

Today, there are more than 100 kinds of dogs in the world.

目前世界上狗的种类已经达到100多种。