问题详情：
Cyril was a small town. The houses there were all made of wood; almost everything in the houses, such as cupboards, tables and chairs were made of wood, too. And all the houses faced south. The town was never peaceful. Fire broke out once a week on summer afternoons. People there were puzzled who the real fireBug (放火者) was.
One day a big fire broke out. It was said that a Negro had jumped out of the house on fire, so the police arrested all the Negroes in the street. However, fire never stopped to break out when the Negroes were in prison.
Watson, a physics teacher didn't believe that the Negroes were the firebugs, for he really knew about those Negroes. He made up his mind to find out who the real firebug was.
One day he was invited to drink in a pub and happened to notice that many bottles and plastic plates were baked by the hot sunrays. Suddenly he realized what the actual fact was. He jumped with joy, saying, “I've got the answer！”
Watson dashed out of the pub to his friend's house nearby, which also faced south. He made an experiment there to prove his idea.
The next Saturday afternoon, Watson asked some policemen and newsmen to come to the house. They were told that the real firebug would be shown there. At that time the sun was shining full into the house and it became hotter and hotter inside the room.
Someone wanted to draw the curtains together, while another was going to use a bottle to drink water, but neither got permission from Watson, who wanted to let the firebug in.
“Now，” said Watson, “this house will soon catch fire.” People looked at each other in surprise. Watson asked them to look at the bottles and focus on the table cloth. After a while the cloth gave off a burning smell and began to catch fire!
The mystery of fire was discovered, but the police wouldn't believe him and insisted that Negroes had been the firebugs. Instead they arrested Watson and put him into prison. But Watson said he would never turn against science.
21．The town was never peaceful, for fire broke out ________.
A. in the afternoon B. in prison
C. at any time D. at night
22．Why did the police arrest all the Negroes?
A. One of them had jumped out of the home on fire.
B. They were thought to be the firebugs.
C. The police hated all the Negroes.
D. The Negroes knew something about the fires.
23．Drinking in a pub, Watson realized ________.
A. he needed to leave the pub
B. he needed to fill the bottles
C. it was too hot in the pub
D. who was the real firebug
24．By making an experiment, they knew the real firebug was ________.
A. the Negroes B. bottles
C. sunrays D. plastic plates
【回答】
ABDC
知识点：*经济文化类阅读
题型：阅读理解
