问题 单项选择题

设文件索引节点中有8个地址项,每个地址项大小为4字节,其中5个地址项为直接地址索引,2个地址项是一级间接地址索引,1个地址项是二级间接地址索引,磁盘索引块和磁盘数据块大小均为1KB字节。若要访问文件的逻辑块号分别为5和518,则系统应分别采用______。

A.直接地址索引和一级间接地址索引
B.直接地址索引和二级间接地址索引
C.一级间接地址索引和二级间接地址索引
D.一级间接地址索引和一级间接地址索引

答案

参考答案:C

解析: 依题意,5个直接地址索引可以表示5×1KB=5KB,其逻辑块号是0-4;一级间接地址索引可以产生的索引项为1024/4=256,一级间接索引可以表示256×1KB=256KB,2个一级间接地是索引表示256×2=512KB,其逻辑块号是5~511;二级间接索引产生的二级间接索引项也为256,因此二级索引表示256×256KB=65536KB,其逻辑块号是512-65535。
由于5>4,因此要访问逻辑块号为5的文件,系统应采用一级间接地址索引。而518>511,要访问逻辑块号为518的文件,则系统应采用二级间接地址索引。

阅读理解

阅读理解。

      When you are curious about something and want to know more about it, you can use the way of asking

questions. Asking questions is the first step to make discoveries and find interesting answers. The following

steps can guide you during the research.

      Step l  Write down the subject that you are interested in on a piece of paper. Just get the main idea down.

For example, you might write: Discover more about robots.

      Step 2  Stop and think for a moment about what you have already known about your subject.

       List what you have already known like the sentences below:

      1. The first robot appeared in the USA in 1959.

      2. A robot can do housework and act as a teacher.

      3. Sometimes a robot catches viruses and causes a lot of problems.

      Step 3 What can you do with what you want to learn?

       By asking questions, start writing down questions about the robots on the paper:

       1. What might robots be like in the future?

       2. What other things can robots do for people?

       3. What kind of power will robots possibly use in five years?

      Step 4 Armed with your list of questions, you can now go to the nearest library or computer to begin

your research. As you learn more about your subject, you'll probably discover some new questions.

      For example, you might discover that robots can help scientists explore dangerous places, like the sea

and outer space. How? What happened? Asking new questions can help you research your subject more

widely.  

      The next time you find something interesting to research, take time to organize your thinking by asking

good questions. And remember that learning more always brings more questions.

1. What does the writer advise us to do when we're curious about something? 

A. To read more books about it.

B. To look it up in the dictionary.

C. To turn to the teacher for help,

D. To raise questions and find the answers.

2. What does the underlined part "Armed with your List of questions" mean?

A. Writing down your list of questions.

B. Discussing your questions with others.

C. Taking your list of questions with you.

D. Putting your list of questions under your arm.

3. What might be the correct order of the steps when you do research?

   ① List what you want to learn.

   ② Find new problems.

   ③ List what you've already known.

   ④ Choose a research subject.

A. ④③①②

B. ④①③②

C. ②③④①

D. ③②①④

4. What might be the best title for this passage?

A. Doing Research on Robots

B. Asking Good Questions While Doing Research

C. Having Interesting Answers on Robots

D. Finding Subjects before Doing Research

多项选择题