问题
选择题
体温计的测温精度能达到0.1℃，这是因为（ ）
A．体温计玻璃泡内的水银比一般温度计的多
B．体温计的测量范围小
C．体温计的尺寸较短
D．体温计玻璃管的内径小，灵敏度高
答案
体温计和常用温度计相比，前者内径很细，而下端的玻璃泡则很大，使得有微小的温度变化，即吸引很少的热量，管中水银上升的高度会非常明显，所以可以测量的更为精密．
故选D．
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体温计的测温精度能达到0.1℃，这是因为（ ）
A．体温计玻璃泡内的水银比一般温度计的多
B．体温计的测量范围小
C．体温计的尺寸较短
D．体温计玻璃管的内径小，灵敏度高
体温计和常用温度计相比，前者内径很细，而下端的玻璃泡则很大，使得有微小的温度变化，即吸引很少的热量，管中水银上升的高度会非常明显，所以可以测量的更为精密．
故选D．
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| Even though it was only October, my students were already whispering about Christmas plans. With each passing day, everyone became more 1 , waiting for the final school bell. Upon its 2 , everyone would run for their coats and go home, everyone except David. David was a small boy in ragged (破旧的) clothes. I had often wondered what kind of home life David had, and what kind of mother could send her son to school dressed so inappropriately for the cold winter months, without a coat, boots, or gloves. But something made David 3 . I can still remember he was always 4 a smile and willing to help. He always 5 after school to straighten chairs and mop the floor. We never talked much. He 6 just simply smile and ask what else he could do, then thank me for letting him stay and slowly head for home. Weeks passed and the 7 over the coming Christmas grew into restlessness until the last day of 8 before the holiday break. I smiled in relief (欣慰) as the last of them hurried out the door. Turning around, I saw David 9 standing by my desk. "I have something for you," he said and 10 from behind his back a small box. 11 it to me, he said anxiously, "Open it." I took the box from him, thanked him and slowly unwrapped (打开) it. I lifted the lid and to my 12 saw nothing. I looked at David's smiling face and back into the box and said, "The box is nice, David, but it's empty." "Oh, no, it isn't," said David. "It's full of love. My mum told me before she died that love was something you couldn't see or touch unless you know it's there." Tears filled my eyes 3 I looked at the proud dirty face that I had rarely given 4 to. After that Christmas, David and I became good friends and I never forgot the meaning 5 the little empty box set on my desk | ||||
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