问题 单项选择题

用二进制加法器对二一十进制编码的十进制数求和,当和的本位十进制数二一十进制编码小于等于1001且向高位无进位时, (14) ;当和小于等于1001且向高位有进位时, (15) ;当和大于1001时, (16)

A.不需进行修正
B.需进行加6修正
C.需进行减6修正
D.进行加6或减6修正,需进一步判别

答案

参考答案:B

解析: 二一十进制编码又被称为BCD码,如果从左到右每位权值分别为8,4,2,1,则称之为 8421码。BCD码一般都是指8421码。在进行计算时,有时会出现进位和计算值超出BCD码的表示范围,即超过10的情况,此时需要进行修正,修正的方法是本位加6,并向高位进1。

阅读理解

阅读理解。

     When I was at university, I studied very hard. But a lot of my friends did very little work. Some did

just enough to pass the exams. Others didn't do quite enough. Fred Baines was such a student. He spent

more time drinking in the Tea House than working in the library.

     Once at the end of the term, we had to take an important test in Chinese. The test had 100 questions.

Beside each question we had to write "True" or "False". While I was studying in my room the night before

the test, Fred was watching TV. Fred usually worried a lot the night before a test. But on that night he

looked very easy. Then he told me of his idea."

     It's very simple. There are 100 questions and I have to get 50 right to pass the test. I'll take a coin into

the room. I haven't studied a Chinese book for months, so I'll toss (掷,扔) the coin. In that way, I'm sure

I'll get half of the questions right."

     The next day, Fred came happily into the examination room. As he sat tossing a coin for half an hour,

he wrote down his answers. Then he left, half an hour before the rest of us.

     The next day, Fred met his Chinese teacher at the school gate. "Oh, good, "he said. "Have you got the

results of the test?" The teacher looked at him and smiled, "Ah, it's you, Baines. Just a minute." Then the

teacher reached his pocket and took out a coin. He threw it into the air, caught in his hand and looked at

it. "I'm sorry, Baines, you failed!".

根据短文内容,判断下列句子是否正确,对的写"T",错的写"F"。

( )1. Fred Baines was a hard-working student.

( )2. They had to take a Chinese test.

( )3. Fred usually worried a lot the night before a test.

( )4. Fred thought hard and wrote down his answers.

( )5. Fred passed the test at last

单项选择题