问题 单项选择题

现代操作系统中都引入了虚拟存储技术。要引入虚拟存储技术需要具备的前提是 ______。

A.有大量的外存

B.程序执行的局部性原理

C.硬件提供地址转换机制

D.选择一种合适的页面调度算法

答案

参考答案:B

解析:[评析] 程序局部性原理是虚拟技术引入的前提。因为进程的某些程序段在进程整个运行期间,可能根本不使用,如出错处理等,因而没有必要调入内存;互斥执行的程序段在进程运行时,根据系统只执行其中一段,如分支语句等。因而各互斥段没有必要同时驻留内存;在进程的一次运行中有些程序段执行完毕,从某一时刻起不再用到,因而没有必要再占用内存区域。

单项选择题
阅读理解

After a very busy afternoon, as I walked into my house, I heard the phone ringing. It was my friend Lydia, upset over an argument with her husband. My usual approach is to offer advice, but this time, extremely tired from chores, I simply pulled off my coat, sat down in a chair and listened to my friend's frustration and sadness. Without the disturbance of judgment or the desire to comfort her, I stayed totally quiet while she talked. Eventually Lydia's depression eased and we said our goodbyes. The next day she phoned to thank me. "I'm so grateful for the way you helped me through this," she said.

At first I was surprised. After all, I had done nothing except be there for her. But after I had my own venting(发泄的) experience with another friend later that evening, I realized that my focused silence had some value. In fact, most relationship experts agree that talk is cheap; it's listening that's rare and valuable. It allows you not only to hear what the other person is saying, but also to have a clear understanding of her thoughts and feelings. And for the speaker, that level of understanding translates into concern and respect.

Unfortunately, listening isn't as easy as it sounds. Thanks to schedules filled with family and work, multitasking has become the barrier(障碍) to listening. My tiredness may have been the only thing stopping me from folding laundry or checking my e-mail while Lydia talked that afternoon.

Another barrier to listening is our listening system: Most of us take in only about half of what's being said during a conversation, according to the International Listening Association. Research shows that we speak at 125 to 150 words per minute, yet think at 500 words a minute. Therefore, because we think much more quickly than we speak, it is easy for us to lose our concentration when listening to speakers.

While it can be hard to focus at times, it's a skill worth developing. With a little practice — employing some techniques— you can become a better listener.

小题1: In Paragraph 2, the author mainly talks about ____.

A.the importance of listening

B.the importance of venting anger

C.her own listening experience

D.her own venting experience小题2:The author uses the result of the research in Paragraph 4 to mainly show that ____.

A.we think much more quickly than we speak

B.we can only understand about half of what we hear

C.there is not much thinking time available while we are listening

D.we lose our concentration easily while we are listening小题3: What will be discussed following the passage?

A.Why listening is valuable.

B.What we should do while listening

C.How to become a good listener

D.How to stop drifting off while listening.