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问题 多项选择题

建设项目竣工环境保护验收应有（）单位参与。

A.建设单位行业主管部门

B.建设项目设计单位

C.建设项目环境影响评价文件编制单位

D.施工单位

E.监理单位

答案

参考答案：A, B, C, D

解析：《建设项目竣工环境保护验收管理办法》第15条建设项目的建设单位、设计单位、施工单位、环境影响报告书（表）编制单位、环境保护验收监测（调查）报告（表）的编制单位应当参与验收。

单项选择题

About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.

What is the main topic of the passage

A．The relationship between a plant’s roots and its shoots.

B．What can be learned by growing roots in isolation.

C．How plants can be grown without roots.

D．What elements are necessary for the growth of plants.
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问答题

如图所示，用细绳将条形磁铁m1竖直吊起，再将它吸引铁块m2，静止后将细绳烧断，m1和m2同时下落，不计空气阻力，在下落过程中，m2的加速度多大？m2受几个力的作用？甲同学认为m2的加速度一定为g，乙同学认为 m2除受到重力外，还受到磁铁对它的吸引力，所以m2受到二个力作用．

你认为它们的说法正确吗？若正确，请说明理由．若不正确请给出正确的答案，并说明理由．
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