Most people think of racing when they see greyhounds（灰狗）and believe they need lots of exercise. They can actually be quite lazy!  Greyhounds are good at fast races but not long-distance running. They do need regular exercise but they like to run for a short burst and then get back on the bed or a comfortable seat. Another misunderstanding is that greyhounds must be aggressive（好斗的）because they are big in size. In fact greyhounds love people and are gentle with children.
Greyhounds can live for 12 – 14 years but usually only race for two or three years, and after that they make great pets. They don’t need a lot of space, don’t make a lot of noise, and don’t eat a lot for their size.
Normally, greyhounds can be as tall as 90 cm. There is, however, a small-sized greyhound, which stands only 33 cm. Greyhounds come in a variety of colors. Grey and yellowish-brown are the most common. Others include black, white, blue, red and brown or a mix of these.
Greyhounds have smooth body coats, low body fat and are very healthy. Because they’re slim（苗条的）they don’t have the leg problems like other dogs the same height . But they do feel the cold, especially since they would much rather be at home in bed than walking around outside.
The text is written mainly      .

A．to tell people how to raise greyhounds

B．to let people know more about greyhounds

C．to explain why greyhounds are aggressive

D．to describe greyhounds of different colors

It can be inferred that greyhounds       .

A．love big doghouses

B．like staying in bed all day

C．make the best guard dogs

D．need some exercise outdoors

Why does the author say that greyhounds make great pets?

A．They are big in size.

B．They live a very long life.

C．They can run races for some time.

D．They are quiet and easy to look after.

If you keep a pet greyhound, it is important _____________.

A．to keep it slim

B．to keep it warm

C．to take special care of its legs

D．to take it to animal doctors regularly