题目内容
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[主观题]
Why we use index in database？ How many indexes is the maximum in onetable as your sugg
Why we use index in database？ How many indexes is the maximum in one
table as your suggestion？
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更多“Why we use index in database？ …”相关的问题
第1题
分块检索中，若索引表和各块内均用顺序查找，则有900个元素的线性表分成（)块最好 In the blocking search, if we use sequential search to the index table and each block, then the linear table which has 900 elements should be divided into （) parts at best.
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第3题
Why should we be careful of the word be？A、“Be” allows for the use of adjectives which ar
Why should we be careful of the word be？
A、“Be” allows for the use of adjectives which are not descriptive.
B、“Be” is rarely used in written English.
C、“Be” is often confused for “bee”.
D、“Be” is often used in a passive manner and does not show action.
第4题
Why do we use the weather satellites to take pictures of the atmosphere？Because__
____．
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A．the weather satellites can do it easily
B．clouds form. there
C．the weather forms there
D．the pictures can forecast the weather
第5题
When expressing meaning, we don’t just use language, we need additional information.Ma
A.Why are the speakers talking to each other？
B.When and where is the discourse taking place？
C.By what means are the speakers interactin
D.Who are they and what is their relationship？
第6题
Why do we use topic sentences？
A．We use it as an extra sentence to make it look like we’ve done more work．
B．We use it to tell the reader what is being talked about in a paragraph．
C．We use it to give a summary of the essay．
D．We use it to state the purpose of the entire paper．
第7题
Why do we use “I suggest” or “I recommend”, rather than “you should” or “you need to”,
in phone communication？
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A.Because they try to influence what “you” think.
B.Because they assert what “I” believe is true.
C.Because they convey the precise meaning.
D.Because they sound trying to offer help.
第8题
Scientists hope that if we can discover __1__ the brain works, the better use we will
be able to put it to. For example, how do we learn language？ Man differs most from all the animals in his ability to learn and use language __2__ we still do not know exactly how this is done. Some children learn to speak and read and write when they are very young compared to __3__ children. But scientists are not sure why this happens. They are trying to find out __4__ there is something about the way we teach language to children which in fact prevents children __5__ learning sooner.
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1)、A.but
B.how
C.from
D.whether
E.average
2)、A.but
B.how
C.from
D.whether
E.average
3)、A.but
B.how
C.from
D.whether
E.average
4)、A.but
B.how
C.from
D.whether
E.average
5)、A.but
B.how
C.from
D.whether
E.average
第9题
（）Rest is the body ’ s natural means to dissolve stress and fatigue. When we are rested, w
e feel calmer and better able to deal with problems that arise. Research has linked sleep deficiency with poor performance and dullness during the day. Missing just 1.5 hours of sleep in one night can decrease alertness by about 33%. 题目: According to the paragraph, why should we have enough time to sleep？
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A．because a good sleep can decrease alertness．
B．because a good sleep can lead to poor performance
C．because a lack of sleep can lead to poor performance
D．because a lack of sleep can make use feel calmer．
第10题
Mobile phones are the items that a lot of people are having today. However，do we really
need to have a mobile phone by our side？
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We could start with the advantages of mobile phones. There are many things that we could do with mobile phones. With the advancement of technology，more and more features are being added to the mobile phones which make them more useful. In addition to making calls，mobile phones also support a wide variety of other services such as text messaging，email，Internet access，business applications，gaming and photography. We can bring them everywhere，and can be reached by others anytime. They make the world smaller，bringing people together no matter where they are.
But we could have some risks when using our mobile phones. We may have accidents when we use them while driving. Some studies show that mobile phones can do harm to our bodies;and materials in mobile phones could damage our environment.
Since there are so many risks，why do we still have mobile phones？This is because these risks or disadvantages can be overcome. For example，while we are driving we can easily pull up our car if we really need to use the phone. Mobile phone manufacturers are reducing the radiation of mobile phones to avoid health risks.
Though there are both pros and cons of using mobile phones，we could easily see that there are more advantages than disadvantages. Moreover，mobile phones are becoming cheaper，which might be another reason why mobile phones are increasingly used today.
1. Which of the following functions is NOT mentioned in the passage？
A. Text messaging.
B. Camera.
C. GPS.
2. What risks might mobile phones cause？
A. Traffic accidents and health problems.
B. Environmental damage.
C. Both A and B.
3. What are mobile phone manufacturers doing to prevent mobile phone users from health risks？
A. They are reducing the radiation of mobile phones.
B. They are trying to persuade people to use mobile phones less.
C. They are developing new models of mobile phones.
4. Why do people still use mobile phones despite their disadvantages？
A. Because people don’t believe that mobile phones have any disadvantages.
B. Because the disadvantages of mobile phones can be avoided.
C. Because people cannot live without mobile phones.
5. According to the last paragraph，why are mobile phones increasingly being used today？
A. They are safer.
B. They have more functions.
C. They are becoming cheaper.
