题目

完形填空。  A sad little boy was in search of happiness and wanted to meet God. On his way, he saw an elderly woman   1   in a park watching some birds. The boy sat down   2    her. He opened his bag to take a drink. He noticed that lady looked    3    , so he offered her a piece of cake.   She accepted and smiled at him. Her   4   was so wonderful that he wanted to see it again. Then he offered her a can of coke. Once again she smiled at him. The boy was pleased!  They   5   there all afternoon, eating and drinking without saying a word.     6   it began 设nA为阿伏加德罗常数的数值．下列说法正确的是（　　） A、1mol 苯含有6nA个C-H键B、标准状况下，22.4L氨水含有nA个NH3分子C、18gH2O含有10nA个电子D、56g铁片投入足量浓H2SO4中生成nA个SO2分子