关于行程缸径比S/D应该是（）。 A.二冲程低速机的S/D比四冲程机大 B.二冲程低

阅读理解。

     The meeting lasted three hours. Mr. Jackson looked at the clock on the wall. It was a quarter to eight.

"The last bus started fifteen minutes ago," thought the man, "It means I'll have to stay in a hotel tonight."

     Mr. Jackson always drove home after work. He lived outside the city. There was something wrong

with his car these days, so he had to take a bus to his office. That afternoon, he had to discuss something

important with others, so he couldn't catch the bus. At last the meeting was over. It began to snow after he

came out of the warm office. He wanted some warm food and soup first. Most restaurants were full of

people and he went into a small one. The waiter came up quickly and showed the menu to him.

     "Some hot soup, please." said Mr. Jackson.

     About twenty minutes later, the young man brought the soup to him. When Mr. Jackson was drinking,

he found something in it. "Come here, boy," he called out, "Look! There's a gray hair in my soup!" " It's

very strange, sir," said the waiter. " It's usually a fly, I remember."

1. Mr. Jackson usually went home _____. [ ]

A. by bus

B. by car

C. by bike

D. on foot

2. _____, so Mr. Jackson had to stay in the hotel. [ ]

A. The last bus left

B. The meeting was very important

C. Something was wrong with his car

D. It was very cold that evening

3. The last bus started at ______. [ ]

A. 7:30

B. 7:45

C. 8:00

D.8:30

4. Mr. Jackson wanted some hot soup first because _____. [ ]

A. the restaurant was very cold

B. he was hungry

C. there was few people in the restaurant

D. he felt cold after he left the warm office

5. The waiter's words mean that _____. [ ]

A. the soup in the restaurant was nice

B. the hair was Mr. Jackson's.

C. there were usually flies in the soup

D. he had to say sorry to Mr. Jackson

Usually John would be late for meetings. But this time,   ____ to my surprise, he arrived on time.  

A little        B. much     C. ever       D. even

汽车底盘的功能和组成是什么？

简述计算机病毒的分类方法。

声音信号的带宽按15kHz计算，若采用标准调幅（AM）调制，载频为800kHz，则已调信号的带宽为（）

A.15kHz

B.30kHz

C.815kHz

D.830Hz