题干

小刚设计了一种小鸡孵化器的电路模型,如图所示,在一般情况下,只需灯光照明,温度较低时,则需要加热,电源电压恒为 72V,R 1 为定值电阻,R 2 为发热电阻丝改成的滑动变阻器,其上标有“200Ω 3A”的字样,电流表 A 1 的量程为 0﹣0.6A,电流表 A 2 的量程为 0﹣3A,灯泡上标有“12V 3W”的字样.


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    Growing up in Puerto Rico, our family was no different from so many others. My parents got married after my father came back when the war ended. Both of my parents were struggling with the hard economic realities of the time. But somehow, they found time to cherish those cultural values that shaped our everyday life.
    In our daily life, we celebrated together with our friends or family members every birthday, every graduation, and all holidays with music and dancing, and typical foods. When we visited our family in the countryside—a trip that took about two hours in a car, with five children fighting as to who would get a window or the front seat —we would break into song, and somehow the trip would turn into one full of happiness and fun. We would sing not only interesting children's songs but also beautiful love songs — songs about the love of our country though we didn't understand the meaning of the words many times.
    I came to Philadelphia for the first time in 1973 to do a residency(实习) in family medicine. I remember the many hours of work. I was facing issues of life and death and suffering the clearly social unfairness and issues of poverty and race. These were all worsened by my feeling of cultural differences.
    An important turning point in my life happened one Saturday night when I attended a concert of Puerto Rico singer and composer Antonio Caban Vale. The music showed my familiar rhythms, and the words spoke to my heart. I had found a space to express, celebrate, and share my culture in Philadelphia. Therefore, I believe diversity is seen as an advantage and not as a disadvantage. As a Puerto Rican, I am a mixture of races and I believe in my strength because of this.