如图所示，已知R1=6Ω，U∶U2=4∶1，则R2的阻值是_________Ω，

用绝缘工具将触电者剥离电源时注意别使触电者（）。

A、摔伤；

B、说话；

C、受惊

说一个故事的大意：一个干部起点比较低，然后通过自己的努力，成功了，……问你怎么看待他这样的行为？

Now which are the animals really to be pitied in captivity First, those clever beings whose lively urge for activity can find no outlet behind the bars of the cage. This is most conspicuous, even for the uninitiated, in the case of animals which, when living in a free state, are accustomed to roaming about widely. Owing to this frustrated desire, foxes and wolves housed, in many old-fashioned zoos, in cages which are far too small, are among the most pitiable of all caged animals.
Though pinioned swans generally seem happy, under proper care, by hatching and rearing their young without any trouble, at migration time things become different: they repeatedly swim to the lee side of the pond, in order to have the whole extent of its surface at their disposal, trying to take off. Again and again the grand preparations end in a pathetic flutter of their half wings ; a truly sorry picture !
This, however, rarely awakens the pity of the zoo visitor, least of all when such an originally highly intelligent and mentally alert animal has deteriorated, in confinement, into a crazy idiot, a very caricature of its former self. Sentimental old ladies, the fanatical sponsors of the societies for Prevention of Cruelty to Animals, have no compunction in keeping a grey parrot in a relatively small cage or even chained to a perch. Together with the large corvines, the parrots are probably the only birds which suffer from that state of mind, common to prisoners, namely, boredom.

Which is the "lee side" of the pond

A．The side the wind is blowing from.

B．The side which is sheltered from a storm.

C．The side the wind is blowing towards.

D．The side where the water is the deepest.

( )又称城市快速干道，是城市中为联系城市各组团中、长距离快速机动车交通服务的道路，属全市性交通主干道，不宜穿越城市中心和生活居住区。

A．主干路

B．全市性干道

C．次干路

D．快速路

可用于任何分布类型的资料，但实践中常用于偏态分布资料和分布两端无确定值的资料的理论是（）。

A.轨迹交叉理论

B.事故因果连锁理论

C.中位数理论

D.事故频发倾向理论