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更多“Why is the access burst specia…”相关的问题
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.
给定自然数集合N的下列子集:
求下列集合:，
a)A∪(BU(CUD)).
b)A∩(B∩(C∩D)).
c)B-(AUC).
d)(~A∩B)UD。
男性，46岁，头痛、头晕半年，伴视物不清，恶心、呕吐1周。Bp14kPa。Hb70gL。尿蛋白(2+)，沉渣RBC3～Hp，BuN32mmolL，Scr854μmolL，Ccr8mLmin，CO2-CP14μmolL。B超双肾体积缩小。该患者的透析指征是:
A、Ccr8mLmin
B.双肾体积缩小
C、CO2-CP14mmolL
D.恶心、呕吐、食欲下降
E、BuN36μmolL,Scr854μmolL
