已知△ABC∽△A′B′C′，△ABC与△A′B′C′的相似比为k．（1）如果C

美国科学家合成了含有N₅⁺的盐类，含有该离子的盐是高能爆炸物质，该离子的结构呈“V”形，如图所示。以下有关该物质的说法中正确的是(  )

A．每个N₅⁺中含有35个质子和36个电子

B．该离子中有非极性键和配位键

C．该离子中含有2个π键

D．与PCl₄⁺互为等电子体

However difficult you find it to arrange your time, it will pay off in the long run if you set aside a certain part of the day for studying － and stick to it. __小题1:__ But don't forget to make sure that you have enough left for recreational activities or simply to be “with” yourself: reading a novel or watching a television programme.

As part of your weekly schedule, it is also advisable to consider exactly what you have to do in that week, and make sure that you handle the most significant tasks first. __小题2:__

On a physical level, make sure you have an area or space for studying. __小题3:__ If you always study in the same place, preferably a room of your own, you will find it easier to adjust mentally to the activity when you enter that area. You should have everything that you might need at hand.

Make sure that all the physical equipment that you use, such as a desk, chair etc. is at good height for you. If you use a personal computer, there are plenty of guidelines available from the movement on angles, lighting and the like.   __小题4:__

If you are working on topic your teacher has set, but finding it hard to concentrate, it may be that you actually need to take your mind right off it for a period of time.  __小题5:__ After a period away from the test, having not thought about it at all, you may return to it refreshed and full of ideas.

A．It's wise to leave the easier or less urgent areas of your work until later.

B．It's all too easy to read something and then forget where it came from.

C．Consult these and avoid the typical student aches and pains.

D．“Airing the mind” can work wonders sometimes.E．Make use of equipment that is available to you .

F．It is best to make a weekly schedule.

G．Don't do it just anywhere.

在下图所示的实验装置中，实验开始一段时间后，观察到的现象不正确的是(　　)

A．苹果块会干瘪

B．胆矾晶体表面有“白斑”

C．小试管内有晶体析出

D．pH试纸变红

预防尿酸盐结石可服用（）。

A.氧化镁或维生素B₆

B.氯化铵

C.碳酸氢钠和别嘌呤醇

D.卡托普利

E.碱性枸橼酸盐

案例：某年某月某日，某市某化塑制品厂发生火灾，整个厂房被烧毁，造成直接经济损失达127.6万元。当日8时上班后，工人孙某某在该化塑制品厂压球车间门口西侧用电焊焊接压模。焊接现场的周围除一条3m宽的通道外，堆满了袋装成品浮球及废料，还有数个装丙酮、乙烷的铁桶。8时20分左右，拌料员谷某某要在孙某某作业处西侧约1.5m的地方，从铁桶中抽取丙酮，即告诉孙某某要先停止电焊，孙某某同意后便离开作业处。谷某某用塑料管从铁桶中向塑料桶中抽取丙酮，由于操作不当将丙酮洒在水泥地面上，谷某某没有采取任何措施就离开了现场。孙某某回到作业处，没有检查也没有采取任何防护继续电焊。在焊接约3cm长的一段接缝时，电焊溅起的火花将洒在地上的丙酮点燃。孙某某见起火便用正在焊接的方模去压地上的火苗，但火苗仍然四溅。孙某某与另一名工人先后取来3个灭火器，均未启动。火借风势迅速蔓延，整个厂区被大火吞噬。直到11时，大火才被扑灭。事故发生后，某市环翠区人民检察院受理了此案，这起火灾事故是由于违章堆放危险品，遇明火而引起的，谷某某等4人对此负有责任。经现场勘查和调查认定，谷某某、孙某某在生产过程中，违反规章制度，导致发生特大火灾，造成集体财产遭受严重损失，他们的行为触犯了《中华人民共和国刑法》第一百一十四条的规定，构成重大责任事故罪。厂领导孙某某和厂长刘某某身为企业管理人员，不认真履行职责，对厂内事故隐患熟视无睹，对工人的违章作业放任自流，以致由于操作工人在事故隐患区域作业而发生特大火灾，他们的行为触犯了《中华人民共和国刑法》第一百八十七条的规定，构成玩忽职守罪。（说明：本题前3道题为单选题，后5道题为多选题。）

依据《火灾统计管理规定》，这起事故构成()火灾。

A．一般

B．重大

C．特大

D．特别重大

E．特级