题目

听材料，回答问题。 （1） Where does the conversation probably take place? A . At a drugstore. B . At a clinic. C . At home. （2） How long has the toothache been lasting? A . A week. B . A month. C . A year. （3） What did the woman ask the man to do immediately? A . Take some medicine. B . Make an appointment. C . Go for an X-ray. 答案：A A A如图，⊙O是△ABC的外接圆，BC为⊙O直径，作∠CAD=∠B，且点D在BC的延长线上，CE⊥AD于点E．（1）求证：AD是⊙O的切线；（2）若⊙O的半径为8，CE=2，求CD的长．