Linda has been a vegetarian for years. She stopped eating meat because of how she felt. As she told her doctor, she always felt tired. Her doctor looked her over and told her to eat less meat. She bought a vegetarian cookbook and decided to "go all the way". She still eats eggs and cheese sometimes; now, however, most of her food is vegetables, fruits, and grains (谷类). Linda became a vegetarian to improve her health.
Nancy is an animal lover. Nancy grew up on a farm where there were cows and chickens. As she grew older, she started to eat less meat One day she realized that she had stopped eating meat. She thinks it is not right to kill animals for food.
When Mark was a student, he had a careful plan of how to spend money. The little money that he had for food, he spent on rice, cheap vegetables. He learned to be a very good cook. Now Mark is a successful engineer, but he still eats simple foods, and no meat.
Roy is an environmentalist He knows that the population is increasing faster and faster, but the land for growing food is not increasing at all. He knows that it takes sixteen kilos (克) of grain to make one kilo of meat; he thinks about the fifteen kilos of grain that are wasted if he eats meat "Somewhere, " he says, "someone hasn't got enough to eat and is dying. How can I enjoy a thick steak (牛排)?" Mark's ideas about what is right and wrong make him a vegetarian
According to the passage, a vegetarian usually will not eat _____ .

Linda became a vegetarian because ______ .
A .her doctor asked her to do so
B. she was badly ill
C she enjoyed eating vegetables
D. she wanted to be healthier.
Which of the following is TRUE?

A．Mark became a vegetarian when he was a student.

B．We aren't sure when Roy became a vegetarian.

C．Nancy became a vegetarian when she was old.

D．Roy doesn't like steak at all

What is the main idea of the passage?

A．people choose to be vegetarians for different reasons

B．people become vegetarians because they don't like meat

C．meat is not good for one's health

D．we had better become vegetarians