题目内容：

下列短文中有五处需要添加小标题。请你从 A、B、C、D、E 和 F 中选出符 合各段意思的小标题。选项中有一项是多余选项。

1.

Many kinds of birds live in the United States, but the number of the birds is becoming smaller and smaller every year. One of the leading reasons is the growing number of pet cats. By keeping your pet cats in your home, you can help give birds a better possible chance to live.

2.

Of the 90 million pet cats in this country, about two-thirds are allowed to go outside. It is said that these cats kill hundreds of millions of birds each year as well as billions of small animals such as rabbits and field mice.

3.

They can also bring illness to the animals that live in people’s yard, and further weaken(变弱) the health of the natural populations.

4.

Allowing pet cats to go outside is not just bad for birds and wildlife(野生动物). It is bad for the cats themselves, too. Outdoor cats can get sick very easily. They may be in danger from traffic and attacks(攻击)from other animals. In fact, outdoor cats usually don’t pass the age of five, while indoor cats often live to be 17 or older.

5.

Keep your pet cat inside! If you raise a young cat, it’s your duty to let it play inside.

A. You should let your cat inside.

B. Going outside is bad for cats, too.

C. Keeping a cat is good for you.

D. The birds are fewer and fewer in America.

E. Cats can bring illness.

F. Cats kill many birds and small animals every year.