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问题 选择题

下列离子方程式书写正确的是（　　）

A．实验室用大理石和盐酸制取CO2：CO32-+2H+=H2O+CO2↑

B．铁和盐酸反应制氢气：2Fe+6H+=2Fe3++3H2↑

C．AlCl3溶液中加入过量NaOH溶液：Al3++3OH-=Al（OH）3↓

D．SiO2与NaOH溶液反应：SiO2+2OH-=SiO32-+H2O

答案

A．盐酸酸性强于碳酸，碳酸钙可以和盐酸反应，实验室用大理石和盐酸制取CO2离子反应为：CaCO3+2H+=Ca2++H2O+CO2↑，故A错误；

B．铁和盐酸反应Fe+2HCl=FeCl2+H2↑，反应的离子方程式为：Fe+2H+═Fe2++H2↑，故B错误；

C．向AlCl3溶液中加入过量的NaOH溶液 Al3++3OH-═Al（OH）3↓、Al（OH）3+OH-═AlO2-+2H2O，总的反应为Al3++4OH-=AlO2-+2H2O，故C错误；

D．二氧化硅与氢氧化钠反应SiO2+2NaOH═Na2SiO3+H20，二氧化硅是氧化物写化学式，氢氧化钠是易溶于水的强碱，拆成离子，硅酸钠是易溶于水的盐拆成离子，水是氧化物写化学式，所以离子反应为SiO2+2OH-=SiO32-+H2O，故D正确，

故选D．

单项选择题

肝炎病人眼结膜黄染的原因是（）

A.血肿胆固醇增高

B.血中二氧化碳增高

C.血中氧含量增高

D.血中胆红素增高

E.红细胞破坏
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单项选择题

When a disease of epidemic proportions threatens the public, scientists immediately get to work, trying to locate the source of affliction and find ways to combat. Vaccination is one of the effective ways to protect the (1) population of a region or country which may be (2) grave risk. The process of vaccination allows the patient’s body to (3) immunity to the virus or disease so that, if it is encountered, one can fight it (4) naturally. To accomplish this, a small weak or dead (5) of the disease is actually injected into the patient in a controlled environment, (6) his body’s immune system can learn to fight the invader (7) . Information (8) how to penetrate the disease’s defenses is (9) to all elements of the patient’s immune system in a process that occurs naturally, in which genetic information is passed from cell to cell. This makes sure that (10) the patient later come into contact with the real problem, his body is well equipped and trained to (11) with it, having already done so before.

There are, however, dangers (12) in the process. (13) , even the weakened version of the disease contained in the vaccine proves (14) much for the body to handle, resulting in the immune system (15) , and, therefore, the patient’s death. Such is the case of the smallpox vaccine, (16) to eradicate the smallpox epidemic that nearly (17) the whole Native American population and killed massive numbers of settlers. (18) 1 in 10,000 people who receive the vaccine (19) the smallpox disease from the vaccine itself and dies from it. Consequently, the process, which is truly a (20) , may indeed hide some hidden curses.

9（）

A.transmitted

B.transferred

C.transported

D.transformed
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