如图甲所示的装置中,轻质杠杆AB可绕0点在竖直平面内转动,3AO= OB,一个棱

题型:计算题

问题:

如图甲所示的装置中,轻质杠杆AB可绕0点在竖直平面内转动,3AO= OB,一个棱长为20cm的正方体铜块完全浸没在水中,当在杠杆B端用细钢丝挂重为112N的重物G时,杠杆AB恰处于水平平衡;若利用此装置提拉一个物块A,质量为40kg的小明用力拉住杠杆B端使杠杆水平平衡,如图乙所示,已知物块A的体积为40dm3。若杠杆的质量、细钢丝的质量与摩擦均忽略不计(g取10N/kg,ρ=8.9g/cm3),求:

(1)此装置中动滑轮的重G

(2)小明所能吊起物块A的最大质量mA

考点:杠杆的平衡条件密度的计算动滑轮及其工作特点
题型:计算题

根据《土地管理法》的规定,工程建设征用耕地时,若支付的土地补偿费和安置补助费,不能使需要安置的农民不能保持原有生活水平的,经省、自治区、直辖市人民政府批准,可以增加安置补助费,但是,土地补偿费和安置补助费总和不得超过土地被征收前三年平均年产值的()倍。

A.15

B.20

C.30

D.36

题型:计算题

解剖学方位的描述,错误的是

A.近头为上
B.近足侧为下
C.近腹面为前
D.近肢侧为近端
E.近正中矢状面为内侧

题型:计算题

World Water Shortage


A new study warns that about thirty percent of the world’s people may not have enough water by the year 2025.
A private American organization called (1) Action International did the new study. It says (2) than three-hundred-thirty-five-million people (3) enough water now. The people live in twenty-eight (4) . Most of the countries are in Africa or the (5) East.
P-A-I researcher Robert Engelman says (6) the year 2025, about three-thousand-million people (7) lack water. At least 18 more countries are (8) to have severe water problems. The demand (9) water keeps increasing. Yet the amount of water on Earth (10) the same.
Mr. Engelman says the population in countries that lack water is (11) faster than in other parts of the world. He says (12) growth in these countries will continue to (13) .
The report says lack of water in the future may (14) in several problems. It may increase health (15) . Lack of water often means drinking (16) not safe. Mr. Engelman says there are problems (17) over the world because of diseases, such as cholera, (18) are carried in water. Lack of water may also result (19) more international conflict. Countries may have to (20) for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.

题型:计算题

区域经济集团化同世界经济一体化是当今世界经济发展两种截然对立的趋势。 ( )

题型:计算题

结构化方法工资阶段划分为提出任务、初步调查、可行性分析、详细调查、系统的逻辑设 计、【 】、系统实施及系统的运行和维护。

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