与中的“1”关系密切的是( ) A.质子数、电子总数 B.元素化学性质、化合价

题型:选择题

问题:

中的“1”关系密切的是(  )

A.质子数、电子总数

B.元素化学性质、化合价

C.物质状态、电子层数

D.原子结构、中子数

考点:原子结构示意图离子结构示意图
题型:选择题

要锯一块正方形的木料,使木料的面积恰好等于半径是2cm的圆面积,则锯成的正方形木料的边长为______cm.

题型:选择题

男性,40岁,2年来阵发性心悸,2小时前又发作,心电图可见连续出现的快速的QRS波群,QRS波群形态与时间正常,其前后未见P波,节律完全规整,频率为180次/分,ST段稍下移,应诊断为().

A.阵发性窦性心动过速

B.阵发性室上性心动过速

C.阵发性室性心动过速

D.阵发性房性心动过速

E.心房扑动

题型:选择题

锅炉启动初期,开启锅炉对空排汽的目的是()。

A.保护过热器

B.保护再热器

C.回收工质

D.减少噪音

题型:选择题

Questions 26 to 30 are based on the following passage.

Exercise is one of the few factors with a positive role in long-term maintenance of body weight. Unfortunately, that message has not gotten through to the average American, who would rather try switching to “light” beer and low-calorie bread than increase physical exertion. The Centers for Disease Control, for example, found that fewer than one-fourth of overweight adults who were trying to shed pounds said they were combining exercise with their diet.

In rejecting exercise, some people may be discouraged too much by caloric-expenditure charts: for example, one would have to briskly walk three miles just to work off the 275 calories in one delicious Danish pastry (小甜饼). Even exercise professionals concede half a point here. “Exercise by itself is a very tough way to lose weight,” says York Onnen, program director of the President’s Council on Physical Fitness and Sports.

Still, exercise’s supporting role in weight reduction is vital. A study at the Boston University Medical Center of overweight police officers and other public employees confirmed that those who dieted without exercise regained almost all their old weight, while those who worked exercise into their daily routine maintained their new weight.

If you have been sedentary (极少活动的) and decide to start walking one mile a day, the added exercise could burn an extra 100 calories daily. In a year’s time, assuming no increase in food intake, you could lose ten pounds. By increasing the distance of your walks gradually and making other dietary adjustments, you may lose even more weight.

What is said about the average American in the passage? ()

A.They tend to exaggerate the healthful effect of “light” beer.

B.They usually ignore the effect of exercise on losing weight.

C.They prefer “light” beer and low-calorie bread to other drinks and food.

D.They know the factors that play a positive role in keeping down body weight.

题型:选择题

以下不属于实验动物携带的人畜共患传染病病原体的是:()

A.狂犬病毒

B.汉坦病毒

C.梅毒螺旋体

D.马尔堡病毒

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