题干

已知C3N4晶体具有比金刚石还大的硬度,且构成该晶体的微粒间只以单键结合.下列关于C3N4晶体的说法错误的是(   )

A:该晶体属于原子晶体,其化学键比金刚石更牢固

B:该晶体中每个碳原子连接4个氮原子、每个氮原子连接3个碳原子

C:该晶体中碳原子和氮原子的最外层都满足8电子结构

D:该晶体与金刚石相似,都是原子间以非极性键形成空间网状结构

上一题 下一题 0.0难度 选择题 更新时间:2013-03-18 10:18:38

答案(点此获取答案解析)

D

同类题4

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。选项中有两项为多余选项。

Breaking theHabit of Comparing Yourself with Others

   If  you took the strengths of others, and compared them with your weaknesses, youwould feel rather upset. This is what most of us do at one time or another—andsome of us do pretty often. It's a sure­fire recipe for a drop inself­confidence and for unhappiness. ____Here are some tips that might behelpful to you:

   Awareness.Most often we make these social comparisons without realizing we're doing them.It's a natural act, I suppose, and as a result it's something that is donewithout consciousness.____Bringthe thought to your consciousness by being on the lookout for them. If youfocus on these thoughts for a few days, it gets much easier with practice, andsoon it won't be hard to notice.

   Stop yourself. Once you realize you're doing these comparisons, giveyourself a pause.____Justacknowledge the thought, and gently change focus.

   Count your blessings. A better focus is on what you do have, on what you arealready blessed with.____ Think about how lucky you are to have what youhave, to have the people in your life who care about you, to be alive.

    Focus on your strengths. Instead of looking at your weaknesses, ask yourself whatyour strengths are. Celebrate them ! Be proud of them. Don't brag, but feelgood about them and use them to your best advantage.

____ Sometimes we try to criticize others just tomake ourselves look or feel better. Attacking someone else for your benefit isdestructive. It forms an enemy when it could form a friend. In the end, thathurts you as well. Instead, try to support others in their success—that willlead to more success on your part.

a.Don't knock others down.

b.Don't blame yourself or feel bad.

c.So the solution is to become conscious.

d.Helping others means helping yourself.

e.Count what you have, not what you don't.

f.It is important to try to find out your strengths.

g.So how do you break this cycle of comparing yourself withothers?