However,although all the ingredients for a killer-virus scenario

However,although all the ingredients for a killer-virus scenario do undoubtedly exist,it's hard to find a medical expert who believes it's likely that the entire human race will be wiped out by one lethal strain.They tend to put it on a par with the likelihood of us being exterminated by a killer asteroid impact.
【正确答案】：然而，尽管造成杀手病毒侵袭的各种可能性确实存在，却很少有医学专家相信整个人类将被一种致命病毒所毁灭。【解析】原句是主从复合句，前半句是让步状语从句，其中ingredients原意为“成分，要素”，在此理解为“可能性”；后半句中it是形式主语，真正的主语是to find a medical expert,who引导的定语从句修饰expert，汉译时将其译作谓语结构，原来的宾语expert变为主语。