题目

When I lived in Spain, some Spanish friends of mine decided to visit England by car. Before they left, they asked me for advice about how to find accommodation. I suggested that they should stay at bed and breakfast houses, because this kind of accommodation gives a foreign visitor a good chance to speak English with the family. My friends listened to my advice, but they came back with some funny stories. We didn't stay at bed and breakfast houses, they said, because we found that most families were away on holiday. I thought this was strange. Finally I understood what had happened. My 下列实验操作过程中，不需要使用烧杯的是（　　）A．粗盐提纯B．稀释浓硫酸C．实验室用高锰酸钾制取氧气D．用固体溶质配制一定溶质质量分数的溶液