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【单选题】
下列关于索引的叙述正确的是_____。
A.
可以根据需要在基本表上建立一个或多个索引,从而提高系统的查询效率
B.
一个基本表最多只能有一个索引
C.
建立索引的目的是为了指定别名,从而使别的表也可以引用
D.
一个基本表上至少要存在一个索引
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参考答案：
举一反三
【单选题】In the United States, old people who no longer have an income or suffer from a loss of physical abilities are often forced to give up living alone. They must leave their homes and depend on someone el...
A.
In the United States, old people who no longer have an income or suffer from a loss of physical abilities are often forced to give up living alone.
B.
They must leave their homes and depend on someone else to give them a place to live and to take care of their physical needs:
C.
This loss of independence is a major problem for the aged
查看完整题目与答案
【简答题】As regards social conventions, we must say a word about the well-known English class system. “This is an embarrassing subject for English people, and one they tend to be ashamed of, though during the ...
查看完整题目与答案
【单选题】The passage is mainly about ______.
A.
the agriculture revolution
B.
the invention of labor-saving machinery
C.
the development of scientific agriculture
D.
the farming machinery in America
查看完整题目与答案
【单选题】—  ________ invention the wheel is! — I can’t agree more. It is an invention that changed the world.
A.
What a useful
B.
How useful
C.
What a useless
D.
How useless
查看完整题目与答案
【简答题】Old people may choose to live alone for themselves and even embrace this living pattern. But in the deep part of their hearts, they must feel lonely. They need their children to stay with, to talk wit...
查看完整题目与答案
【多选题】We must believe that some people are (luck) than others in their life. People can get a lot of (inform) from the Internet. The old newspapers (throw) away by my brother last week. Some (tradition) chi...
A.
luckier
B.
information
C.
were thrown
D.
traditional
E.
lost
查看完整题目与答案
【简答题】根据句意和首字母提示写出单词。 1. Tom is very helpful. He often gives his s_______ to the old people on the bus. 2. The flu (流感) is a big p_______ in the world now. We must be careful. 3. We all like our English tea...
查看完整题目与答案
【简答题】Must the old people ____________(speak) to politely?
查看完整题目与答案
【简答题】阅读短文还原句子，其中有一多余选项 It’s the best medicine. Many old people like watching TV. You must stay safe when you are playing sports. You must avoid（避免） smoking and drinking. So don’t go to school witho...
查看完整题目与答案
【简答题】My family is not very large. There are only three cats. I’m a white cat. People call me Snow-white. My husband is a black cat. People call him Captain Black Cat. We have a beautiful daughter, her name...
查看完整题目与答案
相关题目：
【单选题】In the United States, old people who no longer have an income or suffer from a loss of physical abilities are often forced to give up living alone. They must leave their homes and depend on someone el...
A.
In the United States, old people who no longer have an income or suffer from a loss of physical abilities are often forced to give up living alone.
B.
They must leave their homes and depend on someone else to give them a place to live and to take care of their physical needs:
C.
This loss of independence is a major problem for the aged
查看完整题目与答案
【简答题】As regards social conventions, we must say a word about the well-known English class system. “This is an embarrassing subject for English people, and one they tend to be ashamed of, though during the ...
查看完整题目与答案
【单选题】The passage is mainly about ______.
A.
the agriculture revolution
B.
the invention of labor-saving machinery
C.
the development of scientific agriculture
D.
the farming machinery in America
查看完整题目与答案
【单选题】—  ________ invention the wheel is! — I can’t agree more. It is an invention that changed the world.
A.
What a useful
B.
How useful
C.
What a useless
D.
How useless
查看完整题目与答案
【简答题】Old people may choose to live alone for themselves and even embrace this living pattern. But in the deep part of their hearts, they must feel lonely. They need their children to stay with, to talk wit...
查看完整题目与答案
【多选题】We must believe that some people are (luck) than others in their life. People can get a lot of (inform) from the Internet. The old newspapers (throw) away by my brother last week. Some (tradition) chi...
A.
luckier
B.
information
C.
were thrown
D.
traditional
E.
lost
查看完整题目与答案
【简答题】根据句意和首字母提示写出单词。 1. Tom is very helpful. He often gives his s_______ to the old people on the bus. 2. The flu (流感) is a big p_______ in the world now. We must be careful. 3. We all like our English tea...
查看完整题目与答案
【简答题】Must the old people ____________(speak) to politely?
查看完整题目与答案
【简答题】阅读短文还原句子，其中有一多余选项 It’s the best medicine. Many old people like watching TV. You must stay safe when you are playing sports. You must avoid（避免） smoking and drinking. So don’t go to school witho...
查看完整题目与答案
【简答题】My family is not very large. There are only three cats. I’m a white cat. People call me Snow-white. My husband is a black cat. People call him Captain Black Cat. We have a beautiful daughter, her name...
查看完整题目与答案
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