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问题 选择题

利用标有“6V，3W”的灯泡、“6V，6W”的灯泡与理想电压表和理想电流表连接成如图（a）所示的实验电路，其中电源电动势E=9V，图（b）是通过两个灯泡的电流随两端电压变化的曲线，当其中一个灯泡正常发光时（　　）

A．电流表的示数为1A

B．电压表的示数约为6V

C．电路输出功率为4.5W

D．电源内阻为2

答案

答案：D

由图乙可知，两灯泡串联，电压表测L2两端的电压，电流表测电路中的电流；

由甲图象可知，L2正常发光的电流为1A，L1的正常发光电流为0.5A，

∵串联电路各处的电流相等，

∴两灯串联在电路中，只有一灯正常发光时，则一定是L1正常发光；

此时电路中的电流I=0.5A，

由图甲可知L2两端的电压U2=2V，即电压表的示数为2V，L1两端的电压U1=6V，

电源电压U=U1+U2=2V+6V=8V，内阻为2

电路中消耗的总功率P=UI=8V×0.5A=4W．

多项选择题

可导致药源性肝损害（）

A.氟康唑

B.辛伐他汀

C.利福平

D.对乙酰氨基酚

E.罗红霉素
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问答题

Green space facilities are contributing to an important extent to the quality of the urban environment. Fortunately it is no longer necessary that every lecture or every book about this subject has to start with the proof of this idea. (46) At present it is generally accepted, although more as a self-evident statement than on the basis of a closely-reasoned scientific proof. The recognition of the importance of green space in the urban environment is a first step on the right way. (47) This does not mean, however, that sufficient details are known about the functions of green space in towns and about the way in which the inhabitants are using these spaces. As to this rather complex subject I shall, within the scope of this lecture, enter into one aspect only, namely the recreative function of green space facilities.
(48) The theoretical separation of living, working, traffic and recreation, which for many years has been used in town-and-country planning, has in my opinion resulted in disproportionate attention for forms of recreation far from home, whereas there has been relatively little attention for improvement of recreative possibilities in the direct neighborhood of the home. (49) We have come to the conclusion that this is not right, because an important part of the time which we do not pass in sleeping or working is used for activities at and around home. So it is obvious that recreation in the open air has to begin at the front door.
(50) The urban environment has to offer as many recreation activities as possible, and the design of these has to be such that more obligatory activities can also have a recreative aspect. The very best standard of living is nothing if it is not possible to take a pleasant walk in the district, if the children cannot be allowed to play in the streets, because the risks of traffic are too great, if during shopping you can nowhere find a spot for enjoying for a moment the nice weather, in short, if you only feel yourself at home after the front door is shut.
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