如图所示电路中,电源电压保持12伏,L1、L2、L3的电阻分别为4Ω,6Ω、8Ω

题型:问答题

问题:

如图所示电路中,电源电压保持12伏,L1、L2、L3的电阻分别为4Ω,6Ω、8Ω.

求:

(1)S1、S2都断开时,电流表和电压表的示数.

(2)S1、S2都接通时,整个电路消耗的电功率.

考点:欧姆定律及其应用电功率的计算
题型:问答题

The six-year-old Billy was seriously ill.

“Billy, what do you wish to do in the future?”

“Mom, I always want to be a fireman.”

His mom went to a fire station. She told a fireman about her son. She asked if it might be possible to give him a ride in a fire engine(消防车). The fireman said, “We can do better. We’ll  make him an honorary(名誉的)fireman for the whole day. He can come to the fire station, eat with us and go out on all the fire calls. If you give us his sizes, we’ll get a real fire uniform for him.”

Three days later, that fireman dressed Billy in his fire uniform and drove him to the fire station. Billy was so excited. There were three fire calls that day. Billy rode in different fire engines and went out all the three calls.

Billy’s dream came true. He lived three months longer.

小题1: Did Billy want to be a policeman?

小题2: Who dressed Billy in his fire uniform?

小题3:. How many fire calls were there that day?

题型:问答题

判断小儿结核病具有活动性的参考指标是什么

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牙周炎X线片见齿槽骨多呈垂直吸收,牙周创伤X线片见齿槽骨多呈水平吸收。

题型:问答题

()与投射的辐射线量的比率,称为吸收比。

题型:问答题

右图是蛋白质合成示意图,请据图回答下列问题:

写出图中下列编号的名称:

①()

②()

④()

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