(12分)将一个各面上均涂有红色的正方体锯成27个同样大小的小正方体, (1)从

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题型:解答题

问题:

(12分)将一个各面上均涂有红色的正方体锯成27个同样大小的小正方体,

(1)从这些小正方体中任取一个,求其中至少有两个面涂有红色的概率;

(2)从中任取2个小正方体,记2个小正方体涂有红色的面数和为ξ,求ξ的分布列和数学期望.

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题型:单项选择题

1/2, 1/6, 1/12, 1/20 ( )

A.1/28

B.1/30

C.1/32

D.1/34

题型:填空题

干燥机不吃料应该()()等.

题型:单项选择题

根据契税法律制度的规定,下列各项中,免征契税的是()。

A.城镇职工第二次购买公有住房

B.某人购置一套住房

C.某军事单位购置一处房屋用于医疗机构

D.取得荒山土地使用权,用于工业园建设

题型:问答题

The Environment in Perspective:Is Everything Getting Steadily Worse Much of the discussion of environmental problems in the popular press leaves the reader with the impression that matters have been growing steadily worse, and that pollution is largely a product of the profit system and modern industrialization. There are environmental problems today that are both enormous and pressing, but in fact pollution is nothing new. Medieval cities were pestholes—the streets and rivers were littered with garbage and the air stank of rotting wastes. At the beginning of the eighteenth century, a German traveler reported that to get a view of London from the tower of St. Paul’s, one had to get there very early in the morning "before the air was full of coal smoke." Since 1960 there has been progress in solving some pollution problems, much of it the result of concerted efforts to protect the environment. The quality of the air in most Canadian cities has improved. In Toronto, for example, the concentration of suspended particulates, or soot, in the air has fallen dramatically since 1962. To put this figure in perspective, it should be noted that the current health advisory level for the index is 32. At a level of 58, people with chronic respiratory diseases may be affected. At 100, even healthy people may be affected by prolonged conditions, and those with cardiac and respiratory diseases could suffer severe effects Recently in Toronto, the index has exceeded 32 on fewer than half a dozen days annually. Similar improvements have occurred elsewhere in Canada and in other industrialized countries. Even the famous, or rather infamous, "fogs" of London are almost a thing of the past. There have been two high readings of particular note in the British capital in 1959 (when the index rose to 275 and there was a 10 percent increase over the normal number of deaths) and in 1962 (when the index rose to 575 and there was a 20 percent increase in mortality ). But more recently, London’s, cleaner air has resulted in an astounding 50 percent increase in the number of hours of winter sunshine. In short, pollution problems are not a uniquely modem phenomenon, nor is every part of the environment deteriorating relentlessly. Environmental problems do not occur exclusively in capitalist economies. For example, in the People’s Republic of China, coal soot from factory smokestacks in Beijing envelops the city in a thick black haze. Similarly, smoke from brown-coal furnaces pollutes the air almost everywhere in Eastern Europe. It has been estimated that a third of Poland’s citizens live in areas of "ecological disaster". The citizens of Leipzig, a major industrial city in what was formerly East Germany, have a life expectancy a full six years shorter than the national average. However, we do not mean to suggest that all is well with the environment in market-oriented economies or that there is nothing more to do. While there have been some improvements, serious problems remain. Our world is now subject to a number of new pollutants, most of which are far more dangerous than those we have reduced, even though they may be less visible and less malodorous While environmental problems are neither new nor confined only to capitalist, industrialized economies, these facts are not legitimate grounds for complacency. The potential damage that we are inflicting on ourselves and on our surroundings is very real and very substantial.

题型:单项选择题

在拉延模的常见故障中,拉延模中凹模圆过小,将会导致拉延后工作()。

A.起皱

B.产生裂纹

C.形状不符合要求

D.尺寸不符合要求