问题 单项选择题

磁盘的存取时间一般包括______ 。

A.寻道时间、旋转延迟时间、传送时间

B.寻道时间、等待时间、传送时间

C.寻道时间、等待时间、旋转延迟时间

D.传送时间、寻道时间、等待时间

答案

参考答案:A

解析: 本题考查点是磁盘的存取时间。活动头磁盘的存取访问一般要有三部分时间:首先要将磁头移动到相应的磁道或柱面上,这个时间叫作寻道时间;一旦磁头到达指定磁道,必须等待所需要的扇区旋转到读/写头下,这个时间叫旋转延迟时间;最后,信息在磁盘和内存之间的实际传送时间叫传送时间。一次磁盘服务的总时间就是以上三者之和。

单项选择题
单项选择题

For many people today, reading is no longer relaxation. To keep up their work they must read letters, reports, trade publications, interoffice communications, not to mention newspapers and magazines: a never ending flood of words. In (1) a job or advancing in one, the ability to read and comprehend (2) can mean the difference between success and failure. Yet the unfortunate fact is that most of us are (3) readers. Most of us develop poor reading (4) at an early age, and never get over them. The main deficiency (5) in the actual stuff of language itself—words. Taken individually, words have (6) meaning until they are strung together into phrases, sentences and paragraphs. (7) , however, the untrained reader does not read groups of words. He laboriously reads one word at a time, often regressing to (8) words or passages. Regression, the tendency to look back over (9) you have just read, is a common bad habit in reading. Another habit which (10) down the speed of reading is vocalization—sounding each word either orally or mentally as (11) reads.

To overcome these bad habits, some reading clinics use a device called an (12) , which moves a bar(or curtain) down the page at a predetermined speed. The bar is set at a slightly faster rate (13) the reader finds comfortable, in order to "stretch" him. The accelerator forces the reader to read fast, (14) word by word reading, regression and subvocalization practically impossible. At first (15) is sacrificed for speed. But when you learn to read ideas and concepts, you will not only read faster, (16) your comprehension will improve. Many people have found (17) reading skill drastically improved after some training. (18) Charlie Au, a business manager, for instance. His reading rate was a reasonably good 172 words a minute(19) the training; now it is an excellent 1,378 words a minute. He is delighted that how he can (20) a lot more reading material in a short period of time.

 

第(4)空应选择()

A.training

B.habits

C.situations

D.custom