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问题 问答题

使用电风扇涉及到很多的物理知识，请你回答下面问题：

（1）电风扇在工作过程中，主要发生了哪种形式的能量转化？实现该能量转化的部件是什么？

（2）用电风扇吹潮湿的地板，能使其尽快变干，请你说说其中的道理。

答案

（1）电风扇工作时把电能转化为机械能（动能），实现这种转化的部件是电动机。

（2）电风扇吹潮湿的地板，会加快地板上方空气的流速，使水蒸发加快，地板易变干。

单项选择题

Consider the following descriptions of approaches used in valuing real estate: Approach 1: In this approach, the present value of after-tax cash flows are calculated based on the investor’s required rate of return before the equity portion of the investment is deducted. Approach 2: In this approach, the value of land is estimated and is added to the price that would have to be paid if a property had to be replaced. Approach 3: In this approach, an appraisal price is estimated as the discounted net operating income based on the market required rate of return. Approach 4: This approach relies on examining recent transaction prices from a group of similar properties and depends on a reasonably liquid market. List in order, from Approach 1 to Approach 4, the real estate valuation methods that correspond to each of the four valuation approaches listed above.（）

A. The discounted after-tax cash flow model, the cost method, the income method, and the sales comparison method.

B. The income method, the cost method, the sales comparison method, and the discounted after-tax cash flow model.

C. The income method, the discounted after-tax cash flow model, the sales comparison method, and the cost method.
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单项选择题

承受荷载作用时，构件在其原有形状下的平衡保持为稳定平衡，就满足了（）要求。

A.强度

B.刚度

C.稳定性

D.变形能力
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