阅读理解。
About five hundred years ago, an earthquake (地震) happened in a small village. Luckily for them, nothing
was destroyed (毁坏) and no one was hurt. But a huge stone fell from a nearby mountain and stopped in the
middle of the road.
When the earthquake stopped, many people came to the road and saw the stone. Some of the strongest men
tried to lift the stone out of the road. But they couldn't move it. They tried to push it but failed. They tried to
pull it with ropes but nothing worked.
"Well," they said sadly, "there's nothing we can do about it. We'll have to change the way."
At this time a boy about 12 years old said, "I think I can help you to move the stone away."
"You?" they shouted. "What are you talking about?" The men all laughed at the boy.
The next morning, some people came into the road. One of them shouted, "The stone is gone." More people
ran out to see what had happened. It was true. The stone wasn't on the road any longer. It wasn't even near the
road.
The boy walked over to where the stone had been and said, "I buried it."
The people looked rather surprised. "You see," he said, "I dug a deep hole next to the stone and I dug a small incline (斜坡) up to the stone and the stone rolled (滚) down into the hole itself. Then I covered it with earth."
The villagers shouted, "Clever boy! Clever boy!" And some of them said, "Why didn't we think out this good
idea?"
1. Around 500 years ago, this story happened in a small _____.
A. town
B. village
C. city
D. country
2. After the earthquake, _____.
A. many people in the village died
B. nothing happened
C. the whole village was covered with big stones
D. a huge stone fell down the mountain and stood in the middle of the road
3. The stone was moved out of the road by _____.
A. an old man
B. a young man
C. a boy
D. a girl
4. In the end, the huge stone was _____.
A. in the earth
B. in the house
C. in the river
D. on the road side
5. From the passage, we can see that _____.
A. the boy was stronger than the villagers
B. the villagers were very foolish
C. the boy was very bright and good at thinking
D. the villagers were all proud of the boy before the earthquake happened
2NH3的反应中，在5s中NH3的浓度变化了8mol/L。则NH3的平均反应速率（ ）
＝1.6 mol/(L·s)，答案选C。