Experiments using animals have played a crucial role in the development of modem medical treatments, and they will continue to be necessary as researchers seek to ______ existing ailments and respond to the emergence of new disease.
考查动词辨析。A项alleviate“减轻，缓和”，B项replicate“复制，折叠”，C项dwindle“减少，变小”，D项exploit“开发，开拓，剥削”。空格处填入动词，其宾语是existing ailments“现有的疾病”，结合后面的句子respond to the emergence of new disease“应对新疾病的出现”可知，alleviate符合语境。句意：动物实验在现代医学治疗的发展中发挥了至关重要的作用，在研究人员寻求减轻现有疾病和应对新疾病出现时，这些实验将继续是必要的。因此，该题选择A项正确。
