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问题 单项选择题

下列关于数据库表的说法中错误的是______。

A．可设置长表名，长宇段名

B．可设置匹配字段类型到类，字段验证和记录验证，触发器

C．可设置主索引和候选索引关键字，字段默认倩，显示模式

D．不可用use命令直接打开，必须在数据库设计器中打开

答案

参考答案：D

解析：在Visual FoxPro中，数据库可．以设置长表名，长字段名；可以设置匹配字段类型到类，字段验证和记录验证，触发器；可以设置主索引和候选索引关键字，字段默认值，显示模式；可以用USE命令打开，也可以在数据库设计器中打开，因此本题的正确选项是D。

问答题

在用伏安法测未知电阻R的实验中，电源电压为3v，R的值约为3Ω，滑动变阻器两只，规格分别是“0.2A  50Ω”和“1A  20Ω”；电流表一只（量程0～0.6A和O～3A）；电压表一只（量程O～3V和O～15v），测量时，滑动变阻器应选______；电流表应选______量程；电压表应选______量程．
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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 172words 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.

A．accelerator
B．actor
C．amplifier
D．observer
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