一道英语题Doyouremember__toProfessorSmithduringyourlastvisitAtobeintroducedBhavngintroducedCdoingthatDtohaveintroduced答案为什么是D我觉得选B阿可是答案说是B求解释不好意思打错

　　一道英语题Doyouremember__toProfessorSmithduringyourlastvisit

　　AtobeintroducedBhavngintroduced

　　CdoingthatDtohaveintroduced

　　答案为什么是D

　　我觉得选B阿可是答案说是B求解释

　　不好意思打错了答案是B为什么选B呢