问题 选择题

如图为元素周期表短周期的一部分.关于A~G七种元素的叙述正确的是(  )

A.E、F、G形成的单质中都含有共价键

B.形成的简单阴离子半径:E>C>D

C.B、C、D三种元素的氢化物的稳定性依次减弱

D.A、B、E的氢化物都能跟HNO3发生化合反应

答案

图为元素周期表短周期的一部分,根据元素在周期表中的位置,可推断出A为C元素,B为N元素,C为O元素,D为F元素,E为S元素,F为Cl元素,G为Ar元素,

A.E、F、G形成的单质分别为:S、Cl2、Ar,Ar为单原子分子,不存在共价键,故A错误;

B.C、D、E的阴离子分别为:O2-、F-、S2-,其中O2-、F-核外有2个电子层,S2-有3个电子层,则S2-半径大于O2-、F-,根据核外电子排布相同的离子,核电核数越大半径越小判断离子半径,则有O2->F-,故S2->O2->F-,故B正确;

C.元素的非金属性越强,对应氢化物的稳定性就越大,非金属性B<C<D,B、C、D三种元素的氢化物的稳定性依次增强,故C错误;

D.A、B、E的氢化物分别是CH4、NH3、H2S,只有NH3能与硝酸化合,故D错误;

故选B.

完形填空

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项多余选项。

What is the secret of writing a good letter? Here are two main ones. Don’t try to be fancy. Don’t try to impress your reader. You will be successful if you follow these seven Cs.

Clear. Use short, direct sentences. _____小题1:_____ Talk as if the reader were right there with you. Above all, don’t use an introduction.

Correct. ____小题2:_____ Don’t guess, even for spelling. Refer to your dictionary. If you need to, check a reference(参考) book, too.

Complete. Don’t scatter (分散,散开) our points. ____小题3:_______ This is good organization too.

Courteous(有礼貌的). Be friendly rather than overly(过于) casual. Present your information nicely even if you are complaining about something. In all letters, treat others as you want them to treat you.

Concise(简洁的). Make each point as clearly and briefly as you can.

Conversational. This is really the secret of good writing. ____ 小题4:_______ Such a letter has a natural, friendly tone(语气). Let your personality come through naturally.

Considerate(体贴的). ____小题5:______ Write about what you believe the reader needs or wants to know. Try to be helpful. This will build good feeling towards you.

The seven Cs are about writing letters. But how about school papers? Use the seven Cs. Write as if you are talking to your teacher or professor. You’ll be surprised. You’ll almost instantly become a good writer. And you might even enjoy writing from now on.

A.Just “talk” to the person.

B.Think of the readers’ point of view as you write.

C.Make them easy to understand.

D.Include long sentences in your letter.E. Make sure what you say is correct.

F. Writing should not be taken too seriously.

G. Finish one point completely before going on to the next.

单项选择题