题目

John Snow was born and worked as a __36__ in Great Britain．Exactly, he was an anaesthetist，37  means that he put people to sleep during operation．He also began to experiment using the same drugs to help women when they had   38  ．That is why he became the doctor who  39  Queen victoria to give the birth of her babies．     At the time he lived，cholera was the most  40 disease．Neither its cause，nor its  41  was understood．So many thousands of people died  42  there was an outbreak．John Snow was  43 to help ordinary people   44   from cholera．He  45   t19．下列描述中，错误的是（　　）A．往下水道中倾倒硫酸铜溶液，会进一步加快铁制管道的腐蚀B．镁与稀盐酸反应剧烈，加入醋酸钠晶体可以减慢反应速率C．电解饱和食盐水制氯气时用铁作阳极D．电解法精炼粗铜，用纯铜作阴极