解下列各题:(1)(6-215)×3-612+714(2)12+27+1448-

题型:解答题

问题:

解下列各题:
(1)(
6
-2
15
)×
3
-6
1
2
+
7
14

(2)
12
+
27
+
1
4
48
-15
1
3

(3)已知
25
=x
y
=2
,z是9的平方根,求:2x+y-5z的值.
考点:二次根式的加减乘除混合运算,二次根式的化简
题型:解答题

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).并在答案卡上将该项涂黑。

Urbanization

Until relatively recently, the vast majority of human beings lived and died without ever seeing a city. The first city was probably founded no more than 5,500 years ago.     小题1:. In fact, nearly everyone lived on farms or in tiny rural (乡村的) villages. It was not until the 20th century that Great Britain became the first urban society in history--- a society in which the majority of people live in cities and do not farm for a living.

Britain was only the beginning. 小题2: .The process of urbanization--- the migration (迁移) of people from the countryside to the city--- was the result of modernization, which has rapidly transformed how people live and where they live.

In 1990, fewer than 40% of Americans lived in urban areas. Today, over 82% of Americans live in cities. Only about 2% live on farms.       小题3:   .

Large cities were impossible until agriculture became industrialized. Even in advanced agricultural societies, it took about ninety-five people on farms to feed five people in cities.  _小题4:. Until modern times, those living in cities were mainly the ruling elite(精英) and the servants, laborers and professionals who served them. Cities survived by taxing farmers and were limited in size by the amount of surplus food that the rural population produced and by the ability to move this surplus from farm to city.

Over the past two centuries, the Industrial Revolution has broken this balance between the city and the country.       小题5:. Today, instead of needing ninety-five farmers to feed five city people, one American farmer is able to feed more than a hundred non-farmers.

A.That kept cities very small.

B.The rest live in small towns.

C.The effects of urban living on people should be considered.

D.Soon many other industrial nations become urban societies.E. But even 200 years ago, only a few people could live in cities.

F. Modernization drew people to the cities and made farmers more productive.

G. Modern cities have destroyed social relations and the health of human beings.

题型:解答题

肾血管性高血压占高血压病人总数的()

A.1%~5%

B.5%~15%

C.15%~25%

D.25%~35%

E.35%~50%

题型:解答题

精神分析派心理学家()曾认为人存在一种“集体无意识”,“是指由各种遗传力量形成的一定的心理倾向”

题型:解答题

固体润滑材料与液体润滑材料的散热大小是不一样的。

题型:解答题

关于电力机车的工作原理的叙述,正确的是()。

A.受电弓将线路电网的交流电,经车顶母线,传至车内各电器电路

B.车内各电器电路把交流电转变成直流电供给各轮轴上的牵引电动机

C.牵引电动机驱动轮对转动

D.工作原理是将电能转变成机械能

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