如图所示,一平行板电容器,上极板带正电下极板带负电,中间充满垂直于纸面向里的匀强

题型:选择题

问题:

如图所示,一平行板电容器,上极板带正电下极板带负电,中间充满垂直于纸面向里的匀强磁场.一带电粒子a(不计重力)以一定的初速度由左边界的O点射入电容器,恰好沿直线从区域右边界的O′点(图中未标出)穿出.若撤去该区域内的磁场而其他条件均不变,另一个同样的粒子b(不计重力)仍以相同初速度由O点射入,从区域右边界穿出,则粒子b(  )

A.穿出位置一定在O′点下方

B.穿出位置一定在O′点上方

C.在电场中运动时,电势能减小

D.在电场中运动时,动能减小

考点:带电粒子在复合场中的运动
题型:选择题

A wise man once said that the only thing necessary for the victory of evil is for good men to do nothing. So, as a police officer, I have some urgent things to say to good people. Day after day my men and I struggle to hold back a tidal wave of crime. Something has gone terribly wrong with our once-proud American way of life. It has happened in the area of values. A key ingredient is disappearing, and I think I know what it is: accountability.

Accountability isn’t hard to define. It means that every person is responsible for his or her actions and liable for their consequences.

Of the many values that hold civilization together --- honesty, kindness, and so on --- accountability may be the most important of all. Without it, there can be no respect, no trust, no law --- and, ultimately, no society.

My job as a police officer is to impose accountability on people who refuse, or have never learned, to impose it on themselves. But as every policeman knows, external controls on people’s behavior are far less effective than internal restraints such as guilt, shame and embarrassment.

Fortunately there are still communities --- smaller towns, usually --- where schools maintain discipline and where parents hold up standards that declare: “In this family certain things are not tolerated --- they simply are not done!”

Yet more and more, especially in our larger cities and suburbs, these inner restraints are loosening. Your typical robber has none. He considers your property his property; he takes what he wants, including your life if you annoy him.

The main cause of this breakdown is a radical shift in attitudes. Thirty years ago, if a crime was committed, society was considered the victim. Now, in a shocking reversal, it’s the criminal who is considered victimized: by his underprivileged (被剥夺基本社会权利的) upbringing, by the school that didn’t teach him to read, by the church that failed to reach him with moral guidance, by the parents who didn’t provide a stable home.

I don’t believe it. Many others in equally disadvantaged circumstances choose not to engage in criminal activities. If we free the criminal, even partly, from accountability, we become a society of endless excuses where no one accepts responsibility for anything. We in America desperately need more people who believe that the person who commits a crime is the one responsible for it..

小题1:What the wise man said suggests that it’s __________.

A.unnecessary for good people to do anything in face of evil

B.certain that evil will be widespread if good men do nothing about it

C.only natural for good men to defeat evil

D.desirable for good men to keep away from evil小题2: According to the author, if a person is found guilty of a crime, ________.

A.society is to be held responsible

B.modern civilization is responsible for it

C.the criminal himself should bear the blame

D.the standards of living should be improved小题3:  Compared with those in small towns, people in large cities have ________.

A.less self-discipline

B.better sense of discipline

C.more respect to each other

D.less effective government小题4: The writer is sorry to have noticed that ________.

A.people in large cities tend to excuse criminals

B.people in small towns still stick to old discipline and standards.

C.today’s society lacks sympathy for people in difficulty

D.people in disadvantaged circumstances are engaged in criminal activities小题5: The key point of the passage is that ________.

A.stricter discipline should be maintained in schools and families

B.more good examples should be set for people to follow

C.more attention should be paid to people’s behavior

D.more people should accept the value of accountability

题型:选择题

苹果汁是人们喜爱的饮料。由于饮料中含有Fe2+ 离子,现榨的苹果汁在空气中会由淡绿色变为棕黄色,使Fe2+转变为Fe3+离子。若榨苹果汁时加入维生素C,会可有效防止这种现象的发生。这说明维生素C具有[ ]

A.氧化性

B.还原性

C.酸性

D.碱性

题型:选择题

英国学者巴顿则认为,城市是一个在有限空间地区内的多种经济市场,( )相互交织在一起的网状系统。

A.住房

B.劳动力

C.建筑物

D.运输

E.土地

题型:选择题

对流免疫电泳中,泳向阴极侧的Ig是()

A.IgG1,IgG2

B.IgG3,IgG4

C.IgG1,IgG3

D.IgG1,IgG4

E.IgG2,IgG4

题型:选择题

记名证券交易后,证券从出让人账户转移到受让人账户,从而完成证券登记变更的过程称为( )。

A.证券账户转让登记

B.证券账户变更登记

C.集中交易过户登记

D.非交易过户登记

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