问题 单项选择题

车间噪声监测时若各处噪声值均小于3dB应()。

A. 按声级大小将车间分成几个区域分别检测

B. 按声级大小浆车间分成几个区域,区域之间的声级相差不超过三分贝

C. 选择2个监测点即可

D.选择1~3各监测点即可

答案

参考答案:D

填空题

镁将成为2 1世纪重要的轻型环保材料,我国含有非常丰富的镁资源。

(1)占地球表面积70%的海洋是天然的镁元素宝库,从海水中提取镁的流程如下:①在实验室进行过滤操作时需要用到玻璃棒,其作用是__________________②电解熔融氯化镁的过程中,____②___ 能转化为____③____ 能。

(2)①金属镁是一种较活泼金属,在二氧化碳气体中也能燃烧。燃烧的化学方程式为,此反应类型属于(  ④   )

A.分解反应    B.化合反应    C.置换反应    D.复分解反应

②金属镁在高温下与氮气反应生成氮化镁,在氮化镁中氮元素的化合价为-3。据此写出氮化镁的化学式___________ 。

(3)老师每次做有关镁的实验时都会强调:镁是一种银白色有金属光泽的金属。但拿出的镁条总是有一层灰黑色的",这层灰黑色的外衣是什么物质呢?猜想:小明认为可能是MgO;小赵认为可能是Mg2(OH)2CO3;小花认为可能是Mg(OH)2。小赵认为小明的猜想是错误的,其理由是_____________________________。实验探究:小赵按右图所示装置进行实验,发现试管口有液滴出现,澄清石灰水变浑浊,同时试管内生成白色固体。实验分析:实验后,小赵认为小花的猜测也是错误的,其理由_______________⑦______________________。Mg(OH)2和Mg2(OH)2CO3都可以加热分解,产物均为氧化物,据此请你写出Mg2(OH)2CO3加热分解的化学方程式________⑧________________。

单项选择题

Few people would defend the Victorian attitude to children, but if you were a parent in those days, at least you knew where you stood: children were to be seen and not heard. Freud and his company did away with all that and parents have been bewildered ever since. The child’s happiness is all-important, the psychologists say, but what about the parents’ happiness Parents suffer continually from fear and guilt while their children gaily romp about pulling the place apart. A good "old-fashioned" spanking is out of the question: no modern child-rearing manual would permit such barbarity. The trouble is you are not allowed even to shout. Who knows what deep psychological wounds you might inflict The poor child may never recover from the dreadful traumatic experience. So it is that parents bend over backwards to avoid giving their children complexes which a hundred years ago hadn’t even been heard of. Certainly a child needs love, and a lot of it. But the excessive permissiveness of modern parents is surely doing more harm than good.

Psychologists have succeeded in undermining parents’ confidence in their own authority. And it hasn’t taken children long to get wind of the fact. In addition to the great modern classics on child-care, there are countless articles in magazines and newspapers. With so much unsolicited advice flying about, mum and dad just don’t know what to do any more. In the end, they do nothing at all. So, from early childhood, the kids are in charge and parents’ lives are regulated according to the needs of their offspring. When the little dears develop into teenagers, they take complete control. Lax authority over the years makes adolescent rebellion against parents all the more violent. If the young people are going to have a party, for instance, parents are asked to leave the house. Their presence merely spoils the fun. What else can the poor parents do but obey

Children are hardy creatures (far hardier than the psychologists would have us believe) and most of them survive the harmful influence of extreme permissiveness which is the normal condition in the modern household. But a great many do not. The spread of juvenile delinquency in our own age is largely due to parental laxity. Mother, believing that little Johnny can look after himself, is not at home when he returns from school, so little Johnny roams the streets. The dividing-line between permissiveness and sheer negligence is very fine indeed.

The psychologists have much to answer for. They should keep their mouths shut and let parents get on with the job. And if children are knocked about a little bit in the process, it may not really matter too much. At least this will help them to develop vigorous views of their own and give them something positive to react against. Perhaps there’s some truth in the idea that children who have had a surfeit of happiness in .their childhood appear like stodgy puddings and fail .to make a success of life.

From the last paragraph the conclusion can be drawn that children who enjoy all-important happiness will()

A. stay away from the harmful influence of extreme permissiveness

B. fall victim to deep psychological wounds they experience at childhood

C. give full play to the development of the vigorous views of their own

D. grow up to be more psychologically immature and irresponsible adults