一个导体两端加4V的电压时，通过它的电流为0.5A，则它的电阻值是______Ω，若通过它的电流变为1A，则它的电阻为______Ω，若导体两端的电压变为零，则它的电阻变为______Ω．
已知两端加4V的电压时，通过它的电流为0.5A，
由公式R=
=U I
=8Ω；4 0.5
当电流变为1A，则它的电阻为8Ω；
若导体两端的电压变为零，则它的电阻仍是8Ω；
故答案为：8，8，8．
A few weeks ago，our dog，which we had kept for more than ten years，had to be put down.First，a tumor on her stomach got worse，and she was very ____.Then，the pain in her back got so bad that sometimes she ___ lie down in the middle of a walk and couldn't take another ____. When I first found out，I was very sad and cried a lot.She was more like a sister to me than a ___.But I was also angry at my stepfather，Steve，who told us the ___ a week after it happened.He ____ because he didn't want to worry us，and he didn't want me to get depressed (抑郁的)and fail my exams.I just thought she was ____ at the animals' hospital. I think you know all the ____ that went through my head：She was my dog！Why didn't he tell us earlier？I didn't even get to say goodbye. People in my family have a ____ of keeping things from me to protect me，such as only telling me that my aunt had cancer ____ she had already improved.All I could think was：Not again! I ____ to my mum，and she said，“I know.I'm ____，too.”I opened my mouth to shout.And then she added，“I'm so angry with Steve that he had to ____ through all this on his own.”Hearing my mum's words，I shut up my mouth.I had been so ____ on myself.I hadn't thought about ____ Steve was going through.That dog was his baby.He'd had her for longer than he'd had us—and he had to make the decision to ____ her life，and then kept in silence for an entire ____.All my anger melted away，and all I felt was ____. It makes me realize that we focus so much on ourselves that we ____ the pain of others.At that moment，my mum's words were an incredible ____ that I'll never forget.
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