问题 选择题

下列叙述正确的是……( )

A.两个非金属原子间不可能形成离子键

B.非金属原子间不可能形成离子化合物

C.离子化合物中不可能有共价键

D.共价化合物中可能有离子键

答案

答案:A

两个非金属原子只能通过共用电子对结合,只能为共价键,故A正确。

B错误,非金属原子间可以形成离子化合物,如铵盐。

C错误,如NaOH中O和H之间就是共价键。

D错误,只要化合物中含有离子键,则该化合物就一定是离子化合物。

评注:对A选项,要特别注意到“两个”这两个字的限制,若无“两个”限制,则A就可能错误,如NH4Cl等铵盐,即多个非金属原子可能形成形成离子键。

问答题
单项选择题

Ask any employee at an level in any company what they dislike about their job and somewhere on the list you will find a complaint about the system of performance appraisals. It does seem strange that an idea which was supposed to benefit both individuals and the company should be so universally disliked, but the staff appraisal is now one of the biggest causes of dissatisfaction at work. In the United States there have even been cases of unhappy workers taking their employers to court over appraisal interviews. It is in a company’s interest to combat this situation, but, before reversing the appraisal’s negative associations, an organization needs to pinpoint the underlying reasons which have contributed to them.

Problems with appraisals can fall into two main areas--those arising from the scheme itself and those arising from the implementation and understanding of that scheme. Naturally it is easier to tackle those in the former category; indeed, some companies have developed schemes following legal guidelines. These guidelines suggest that a successful scheme should have a clear appeal process, that any negative feedback should be accompanied by "evidence" such as dates, times and outcomes and that, most importantly, ratings should reflect specific measurable elements of the job requirements.

It is not always necessary to resort to legal advice however. Some changes to current schemes are simply a matter of logic. For instance, if employees are constantly encouraged to work in teams and to assume joint responsibility for their successes and failures, it makes little sense for the appraisals to focus on individuals, as this may lead to resentments and create divisions within the group. It is possible, and in some cases more suitable, to arrange appraisals where performance is rated for the group.

Staff also need to be educated about the best way to approach appraisals. Managers often find that they are uncomfortable being asked to take on a more supportive role than they are used to without having had any training. Those being appraised may see it as a chance to air their grievances and highlight the company’s failings rather than consider their own role. Both parties view the process as a necessary evil, to be gone through once or twice a year, and then forgotten about. The importance given to the appraisal stems from the fact that, despite all the talk of the interview being a chance for management and employees to come together and exchange ideas, set joint targets and improve the way decisions are reached, the reality is that they are often nothing more than the pretext on which pay rises are given, or not given. Pay is, of course, a subject that always leads to problems.

Given the problems associated with staff appraisals, why is it that, with no legal requirement, companies continue to run them The answer is simple, it is impossible to manage something you know nothing about. As any Human Resources manager can tell you, the best way to learn about someone is to talk to them. Effective people management relies on knowledge and appraisals are still the best way to build up that bank of knowledge.

In an ideal world an appraisal is an opportunity to().

A.improve your salary

B.moan about the boss

C.discuss and agree goals

D.meet every six months