在1和81之间插入三个实数a,b,c,使它们构成一个五项的等比数列,则b=___

题型:填空题

问题:

在1和81之间插入三个实数a,b,c,使它们构成一个五项的等比数列,则b=______.

考点:等比数列的定义及性质
题型:填空题

在化学变化中不能再分的粒子是______,C60分子是由______构成,Na2O2中氧元素的化合价是______,干冰是______(选填“纯净物”或“混合物”).

题型:填空题

以下说法错误的是()

A.高蛋白、高脂肪、低纤维素饮食的人群大肠癌发病率低于低蛋白、低脂肪及高纤维素饮食的人群

B.控制体重、积极防治糖尿病、戒烟限酒对预防胰腺癌和胆囊癌有益

C.在膳食中多补充富含维生素、胡萝卜素的新鲜果蔬对食管癌的预防是有帮助的

D.高脂肪、高胆固醇饮食和饮酒都会增加患肺癌的危险性

E.有效预防口腔癌的方法是不咀嚼烟草、槟榔,不吸烟,避免饮酒,尤其是不喝烈性酒

题型:填空题

However urban life strikes you, cities worldwide have been growing ever more rapidly. Some of this growth has happened in the developed world, but the most dramatic increase has been in the Third World. Almost all the world’s population growth over the next 30 years will take place in the cities of developing countries.

By the year 2030, for the first time in history, 60 percent of the world’s people will be living in cities.

This is actually good news in some ways. “Cities are the fundamental building blocks of prosperity(繁荣),” says Marc Weiss, chairman of the Prague Institute for Global Urban Development, “both for the nation and for families.” Industrial and commercial activities in urban areas account for between 50 and 80 percent of the GDP(国内生产总值) in most countries of the world. “There’s the crazy idea that the way to deal with a city’s problems is to keep people out of them.” Weiss continued. “But the problems of the rural life are even more serious than those of the city.” For better or worse, urban-watchers are clear on one point: The quality of life for most people in the future will be determined by the quality of cities. Those cities will be bigger than ever. And yet, population numbers by themselves don’t determine a city’s prospects; after all, Addis Ababa, Ethiopia, and Hamburg, Germany, have the same population. Nor is explosive growth necessarily the determining factor. “City problems,” one authority points out, “mostly have to do with weak, ineffective, and usually unrepresentative city governments.”

小题1:According to the passage, in the year of 2030 _______.

A.there will be many cities having a population of more than 10 million.

B.rural area will be extinct (灭绝).

C.most people will live in cities.

D.the third world will keep up with the developed world.小题2:In the author’s opinion, _________.

A.better city, better life

B.both urban and rural areas will have a large population

C.the larger the population is, the faster a city develops

D.both urban and rural areas have larger GDP小题3:The last paragraph implies that ____________.

A.Public services are ineffective.

B.Cities are increasing too fast.

C.Population is not linked with development.

D.Government should be responsible for the problems in the cities.

题型:填空题

下列情况可引起宽QRS波(>0.12秒)心动过速,但不包括()

A.室性心动过速

B.室上性心动过速伴室内差异性传导

C.室上性心动过速并束支阻滞

D.WPW综合征

E.窦性心动过速

题型:填空题

商业文化的功能主要有()。

A.传导功能

B.展示功能

C.约束功能

D.创新功能

E.增值功能

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