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问题 单项选择题

部门.DBF：部门号C(8),部门名C(12),负责人C(6),电话C(16)职工.DBF：部门号C(8),职工号C(10),姓名C(8),性别C(2),出生日期D部门.DBF：部门号C(10),基本工资N(8.2),津贴N(8.2),奖金N(8.2),扣除N(8.2)

查询所有目前年龄在35岁以上(不含35岁)的职工信息(姓名、性别和年龄),正确的命令是【 】。

A．SELECT 姓名,性别,YEAR(DATE())-YEAR(出生日期)AS年龄FROM职工；　　 WHERE年龄＞35

B．SELECT 姓名,性别,YEAR(DATE())-YEAR(出生日期)AS年龄FROM 职工；　　WHERE YEAR(出生日期)＞35

C．SELECT姓名,性别,YEAR(DATE())-YEAR(出生日期)AS年龄FROM 职工；　　WHEREYEAR(DATE())-YEAR(出生日期)＞35

D．SELECT姓名,性别,年龄：YEAR(DATE())-YEAR(出生日期)FROM 职工；　　WHERE YEAR(DATE())-YEAR(出生日期)＞35

答案

参考答案：C

解析：在SQL SELECT子句中利用AS关键字,可以重新定义字段名,但并不存储在表内,称为虚字段。在设置查询条件时,不能根据新定义的字段名对原数据表设置查询条件。

填空题

(8分)已知A、B均是由两种元素组成的化合物，A中某种元素的质量分数为75%，B是一种淡黄色固体，C、J是同周期元素的气态氢化物，其中C是含氢量最高的烃，X为常见的无色液体。反应生成的水均已略去。它们有如下图所示的关系。

(1)写出化学式：A________，B________，J________。

(2)反应③中每生成1 mol F，转移电子的数目为______________。

(3)反应④的化学方程式为：______________________________。

(4)写出离子方程式：

反应②_______________________________________________；

反应⑤________________________________________________。

(5)反应①中，每1.00 g C与足量的F作用，恢复到25 ℃放出55.6 kJ热量，写出

反应①的热化学方程式                                               。
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单项选择题

(四)

The average person learns most of the 30000 ～40000 words whose meanings he or she recognizes by hearing them or getting familiar with them in the context or simply absorbing them without conscious effort. The best way to build a good vocabulary, therefore, is to read a great deal and to participate in a lot of good talks. There are relatively few words that we learn permanently by purposefully referring to dictionaries or keeping word lists. However, even those extra few are of value, and no one will make a mistake by working on developing a larger vocabulary. Here are some suggestions of how to do it.

Read plenty of good books. When you come across a new word, or a new meaning of an old word, stop and see if you can understand it from its context. If you can’t, and if you can manage without interrupting the thought of the book too much, look it up in a dictionary or ask somebody and then repeat its meaning to yourself a couple of times, If you are really conscientious, write the word and its meaning in a personal vocabulary list—preferably using it in a sentence, or you can keep a special vocabulary notebook. Go over the list from time to time. Further, try to use a new word in writing or conversation a few times over the next several days.

Listen to good talks and be alert to new words you hear or to new meanings of words you already know. Then treat them just as you treat the new words you read.

Learn and be alert to the parts of words: prefixes, suffixes and roots. Knowing them enables you to make intelligent guesses about the meaning of words.

If you are studying a foreign language, be alert to words in that language which relate to words in English. English has inherited or borrowed much of its vocabulary of 500000～600000 words from Latin, Greek, French, Spanish and German.

When you meet a new word in reading, what should you do（）

A．Guess its meaning.

B．Ask somebody.

C．Look it up in a dictionary.

D．All of the abov
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