题目

阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。 JohnSnow was a famous doctor in London, was so expert that he attended Queen Victoriaas her personal physician. But he was famous for (defeat) King Cholera. Cholera was a (dead)disease and neither its cause nor its cure (understand). John Snow wanted to facethe challenge and solve the problem. He suspected that people absorbed thisdisease into their bodies when (have) their meals. So when another severeoutbreak hit London, he began his enquiry. He found that many victims(link)to the out设抛物线y2=2px （p＞0）的焦点为F，经过点F的直线交抛物线于A、B两点，点C在抛物线的准线上，且BC∥x轴．证明直线AC经过原点O．