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问题 选择题

下列物质中，含有氧分子的是（　　）

A．空气

B．H2O

C．CO2

D．SO2

答案

A、空气中含有氧气，氧气是由氧分子构成的，则空气中含有氧分子，故选项正确．

B、H2O是由水分子构成的，不含氧分子，故选项错误．

C、CO2是由二氧化碳分子构成的，不含氧分子，故选项错误．

D、SO2是由二氧化硫分子构成的，不含氧分子，故选项错误．

故选A．

单项选择题

确诊猪带绦虫病的诊断方法主要是

A．粪便直接涂片法查虫卵

B．饱和盐水漂浮法查虫卵

C．粪便水洗沉淀法查虫卵

D．检获粪便中的孕节，观察子宫侧支数

E．以上均不是
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填空题

Today’s lecture is about the mass (1) of the world’s population. There are two major (2) why people are moving to cities. The first reason is (3) . People are moving to the cities because that’s where they can find (4) and earn money. The second reason for the move to cities has to do with (5) of life issues: comfort and (6) . Cities often offer better (7) . And then for many, city life is just more (8) . An interesting consequence of urbanization is that the average (9) of people in the countryside is increasing, while that of the cities is (10) .
Three key (11) can be identified in our cities. First of all, they’re getting bigger. Most cities are bigger now than ever before. Cities are also changing shape. They’re getting (12) , because land is getting more and more expensive. (13) have become a symbol of modern cities.
Cities are also changing shape in other ways. The (14) Model and the (15) Nuclei Model are probably more typical of the cities we know today. They show the urban (16) that’s occurring in contemporary cities.
The third change is that our cities are breaking up into (17) communities, often by (18) group or (19) level. This often means that people stay within their community and do not come into contact with others from different (20) .
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