题干

现在医学上使用的心肺机的功能之一是用“电动泵”替代心脏,推动血液循环.如图所示,其中阀门K1、K2均为单向阀门,阀门K1只能向外自由开启;阀门K2只能向内自由开启,反向则封闭管路;当线圈中的电流从a流向b时,线圈的左端为____(选填“N”或“S”)极,此时活塞将向____(选填“左”或“右”)运动.

上一题 下一题 0.0难度 选择题 更新时间:2018-05-01 12:40:14

答案(点此获取答案解析)

N,右

同类题3

    My earliest memory of dad is grabbing (抓住) his hand while we walked together. As I 1 older, I remembered my father and I listened to many basketball games on the radio. I always fell asleep 2 the game was over. When I woke up in the morning, the score sheet (计分表) with the3score on it would be lying next to me. I'll always remember that.
    On cold mornings my father would drive his bread truck by the house. I used to ride on the floor of that bread truck as he delivered (分送) the bread to the stores. The 4 and the warmth from the bread made me hungry and kept me warm. I'll always remember that.
    My father would attend all my games. One night before an important game my father told me5 that he wouldn't be able to watch the game because he had to deliver the bread and it was a three-hour6from his route. The next day as the game time drew near, I thought about my dad. I happened to look across the field and  7saw his bread truck pulling into the stadium. He tried to make the game. I'll always remember that.
    Years later I became a teacher. I'll never forget the voice on the phone early one morning telling me dad had just been killed in a traffic accident. I could hear my heart beat in my ears. I 8up the phone and went back to my bedroom. After that nothing was very important to me. One day I was on the playground when a little boy walked up to me and grabbed my hand. His hand held mine the9  way I used to hold my father's by the last two fingers. At that moment I found my 10 in life again. You see even though my father was gone, he left something with me. He left me his smile, spirit and touch. My purpose was to use those gifts as he did. From that day I started. I'll always remember that!