Let us be ruthless in our criticism. Let us be cruel to personal

Let us be ruthless in our criticism. Let us be cruel to personal fame. We should also be indifferent to age and rank if these stand in our way. (parallel structure)
【正确答案】：Let us be ruthless in our criticism,cruel to personal fame, and indifferent to age and rank if these stand in our way.
【题目解析】：平行结构(parallel structure)，即把结构相同、意义相关的单词、短语和分句排列在一个或几个相连的句子里。这里ruthless in our criticism,cruel to personal fame, indifferent to age and rank是平行的并列成分。