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问题 选择题

已知a＞b，则下列不等式不一定正确的是（　　）

A．2a-3＞2b-3

B．2-a＜2-b

C．3a-3b+1＞0

D．a2＞b2

答案

A、∵a＞b，∴2a＞2b，∴2a-3＞2b-3一定成立；

B、∵a＞b，∴-a＜-b，∴2-a＜2-b一定成立；

C、∵a＞b，∴3a＞3b，∴3a-3b＞0，∴3a-3b+1＞0一定成立；

D、当a=0，b=-1时不成立．

故选D．

单项选择题

长虹集团提出“以振兴民族工业为己任”的企业口号，在宣传和树立企业良好社会形象的同时，也对其它企业积极投身“振兴民族工业”产生了极大影响，这表明企业文化具有（ ）

A．辐射作用

B．激励作用

C．约束作用

D．凝聚作用
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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.

20（）

A.luck

B.triumph

C.blessing

D.promise
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