一个语法的知识点

Michiko54

如题：就是that引导的定语从句，关系代词that在句中作宾语，要不要省略的问题，感觉有时要省有时又不能省，怎么区分啊？
Some scientists have been critical of the laboratory tests conducted by the Federal Drug Administration on the grounds that the amounts of suspected carcinogens fed to animals far exceeds those that humans could consume
正确答案是far exceed those that humans could consume，这里的that就不能省，因为those的存在，that的补出使得定语从句更为清晰，即便that在定从中做宾语，为什么会因为those呢？

Michiko54

自己顶~~~