我认为你填的不对,应该是whose responsibility was
分成两句通常可以更好理解这种定语从句的结构关系.
1.Those were the assistants.那些人就是助手.
2.The assistants' responsibility was to do the research work in the lab.这些助手的责任就是在实验室里做研究工作.
The assistants' 就是whose的位置.
明白没那of whom responsibility was对不对？这种表达也可以，一把情况下介词加疑问代词的结构也可以代替。这样就可以分成：1.Those were the assistants.那些人就是助手。2.The responsibility of the assistants was to do the research work in the lab.这些助手的责任就是在实验室里做研究工作。 of the assistants 的位置就是of whom