“This one’s for you,” Sergeant (警官) Barstow shouted and left quickly through the back door. I was a little puzzled. I looked out a window of the Ashfordly Police Station and saw an elderly woman come into the building.
“Good morning, Madam,” I said.
“Good morning,” she said pleasantly. “You’re new, aren’t you?”
“Yes, Madam.”
“It’s about that man who’s been annoying me,” she said. “I’ve been here about him before.”
“Could I have your name and address, please?”
“Miss Fraser. Josephine Fraser. I live at 43 Prince Terrace. Now, can you please do something about Jackson?”
“What’s he done, Miss Fraser?”
“Done? He’s thrown garbage all over my stairs again. He must be stopped.”
“Where does he live?”
“Next door, Number 41,” she said.
“I’ll go and see later and warn him off, Miss Fraser.”
“I would be most grateful.” With that she left.
Half an hour later, I reached Prince Terrace. NO. 41 was in a bad state of repair. I knocked. No reply. I entered. The place was deserted. I wondered if the Jackson was a tramp (流浪者). Anyway, it seemed he had left, possibly because of Miss Fraser’s threatening police action. I decided to visit her.
I knocked on her door and it was opened almost immediately. “Ah!” she said gladly. “You’re just in time for coffee.” I followed her inside. Miss Fraser told me more about her battle with Jackson. But when I asked specific questions, it clearly showed that she had never seen Jackson. Finally, I managed to leave.
Sergeant Barstow smiled kindly as I returned. “Nick, did you kick(踢出) Jackson out of that house?”
“Jackson!” I cried. “Who is he?”
“There is no Jackson,” he said. “Miss Fraser is lonely and she likes company. We always let the new young men deal with Miss Fraser. It gives her deep satisfaction. That’s what we are here for, isn’t it — to satisfy the public?”
小题1:Why did Sergeant Barstow leave quickly when Miss Fraser came?
A．Because he wanted to let Nick deal with her alone.
B．Because he had to go and catch Jackson at once.
C．Because he was tired of the elderly woman.
D．Because he knew she would tell a lie.小题2:Miss Fraser told Nick that _____.
A．her neighbor had often caused her trouble
B．it was her first visit to the police station
C．she was looking for Sergeant Barstow
D．someone had broken into her house小题3:Miss Fraser made up the story of Jackson because _____.
A．she liked to play jokes on the policemen
B．she wanted to have someone to talk with
C．she loved to show others her nice coffee
D．she hated Jackson very much
求出⑶另两组同学保持小车及车中的砝码质量M一定，探究加速度a与所受外力F的关系，由于他们操作不当，这两组同学得到的a－F关系图象分别如图1和图2所示，其原因分别是：图1： ；图2： .
，故只有当m<<M时，
，我们才可以用钩码的重力当做拉动小车的外力；
求出，因为公式就说明了a与M的关系，而这正是我们要寻找的。
，说明是m过大（或M过小）而引起的；再由图2可知，当F必须有一定大小时，才能产生加速度，说明没有平衡摩擦力或木板的倾角过小而造成的。