为了比较水和煤油的吸热能力，小明用两个相同的装置做了如图1所示的实验．

B

    John is an American boy. His family is in China now. John likes chocolates (巧克力) very much. But his mother doesn't give him any. They are not good for him, she thinks. But John has a very nice grandfather. The old man loves him very much, and sometimes he buys John some chocolates. Then his mother lets John eat them. She wants to make the old man happy. One Sunday evening John says in his room, "Please, God. Make them give me a big box of chocolates tomorrow. It's my birthday." His mother says, "God can't hear you, my boy." "I know, but my grandfather is in the next room. He can hear."