阅读理解。
We spent a day in the country, picking wild flowers. Our car looked like a flower shop inside! On
the way home we had to stop at traffic lights, and then my wife noticed the cupboard.
It was tall and narrow, and it stood outside a furniture shop. "Buy it," she said at once. "We'll carry
it home on the roofrack (行李架). I've always wanted one like that."
What could I do? Ten minutes later I was ￡20 poorer, and the cupboard was tied on to the
roofrack. The police even stopped traffic to let us through. Carrying furniture was a good idea.
After a time my wife said, "There is a long line of cars behind. Why don't they overtake, I wonder?"
In fact a police car did overtake. The two officers inside looked at us seriously as they passed. But
then with great kindness, they led us through the rush-hour traffic. The police car stopped at our village
church. One of the officers came to me.
I was puzzled. "Thanks, officer," I said. "You've been very kind. I have just down the road."
He was staring at our load: first at the flowers, then at the cupboard. "Well, well," he said, laughing,
"It's a cupboard you've got here! We thought it was…er, something else."
My wife began to laugh. Then the truth hit me like a stone between the eyes. I smiled at the officer.
"Yes, it's a cupboard, but thanks again." I drove home as fast as I could.
1.The writer writes the story in order to ________.
A. praise the police officers
B. thank the other drivers
C. show people are kind to each other
D. tell us their funny experience
2.The writer stopped their car on their way home ________.
A. to buy a cupboard
B. waiting for the lights to turn green
C. to pick wild flowers
D. when they came to a flower shop
3. How much is the cupboard?
A. ￡20
B. ￡40
C. ￡12
D. We don't know
4.The writer's wife began to laugh because _________.
A. she thought the police officers were foolish
B.she was interested in what the police officer said
C.she was glad they were treated kindly
D. she has realized the truth
5. As a matter of fact, the police ________.
A. failed to help the writer
B. did help the writer
C. got the writer into trouble
D. made the writer angry
－L的关系图线由于是直线，设其斜率为k，直流稳压电源的输出电压为U,则计算金属丝电阻率的表达式为__________（用k、d、U表示）