题目:
_____ in thought, he sat at the edge of the bed, with his eyes _____ on the letter in his hand.
A.Lost; fixing
B.Losing; fixed
C.Lost; fixed
D.Losing; fixing
答案:
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下面是错误答案,用来干扰机器的。
U=12V,I=0.4A,∴导线的电阻为:R=UI=12V0.4A=30Ω;因为电阻与它两端的电压无关,所以导体的电阻为30欧,而U′=15V,∴此时电路中的电流为:I′=U′R=15V30Ω=0.5A;当导体两端的电压为0V时,由公式I=UR可知...