流出肾脏的血液成分与流入肾脏的血液成分相比，其特点是（　　）

复数$z=\frac{1}{1+i}$所对应的点在第（ ）象限．

⑴提出问题：并联电路中，各电灯两端的电压有什么关系？

⑵你的猜想是：并联电路中各电灯两端的____；理由是：各个电灯并联在____．

⑶设计实验：用电压表分别测量两个灯泡L₁、L₂以及电源两端的电压，所需的实验器材有：电源、开关、导线、____、____、滑动变阻器．

⑷进行实验：按照电路图连接电路，进行实验测量，记录实验数据．

⑸分析论证：（只要求粗略地写出分析和论证的思路，即怎样得出结论的）用电压表分别测量出电灯连段的电压U₁和U₂，若两者相等，即____．

⑹实验结论：两个灯泡L₁、L₂的电压和电源电压相等．

⑺实验评估：上述实验中，小明只进行了一次测量，得出的结论偶然性的机会很大，为了使实验结论具有普遍性，你将建议小明怎样做？改变电源电压大小或小灯泡的规格，____．

⑻实验回答：如果电源电压为6V，那么根据探究的结论，灯L₁的电压为____V，灯L₂的电压为____V．

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    Swedish businessman Nile Bergqvist is delighted with his new hotel, the world's first igloo(冰屋) hotel.

    ____ (build) in a small town, it has been attracting lots of visitors but soon the fun will be over. In two weeks' time，Bergqvst's ice creation ____ (be) nothing more than a pool of water. “We don't see it as a big problem,” he says. “We just look forward to ____ (replace) it.”

    Bergqvist built his first igloo in 1991 for an art exhibition. It was ____ successful that he designed the present one, ____ measures roughly 200 square meters. Six workmen spent more than eight weeks —piling 1,000 tons of snow onto a wooden base；when the snow froze, the base ____ (remove).

    After their stay, all visitors receive a survival certificate recording their success. ____ no windows, nowhere to hang clothes and temperatures below 0°C, it may seem more like a survival test ____  a relaxing hotel break. “It's great fun,” Bergqvist explains, “as ____ as a good start in survival training.''

    The ____ (popular)of the igloo is beyond doubt：it is now attracting tourists from all over the world. At least 800 people have stayed at the igloo this season even though there are only 10 rooms.