题目

One day, a man was walking in his garden and he found a cocoon (茧). As he watched the cocoon, he    1    a small opening appear. He sat and watched the cocoon for several hours as it         2    to force its body through the little hole. After some time, it seemed to stop making any    3   . It appeared as if it had got as far as it could and could go no further. The man was so    4    to see the butterfly that he decided to help it. Using his hands he opened the cocoon large enough for the butterfly to    5   . He thought to himself, “What a great下列实例中，通过热传递改变物体内能的是A. 用“搓手”的方法取暖B. 用气筒给轮胎打气，气筒壁发热C. 早餐时，用热水给牛奶加热D. 车速过快时，要频繁用力捏车闸，刹车片发烫