The patients __________ all look happy and healthy.A.after whom the nurses lookB.after that the nurses lookC.whom the nurses look afterD.whom the nurses look答案选C，为什么不能选A？
热心网友
楼上所说的理由有误。你问的实际上是介词prep。+关系代词which/whom不能转换成关系代词which/whom/ who 。。。+介词prep。的结构的情况一般来说，当定语从句的连接词由介词prep。+关系代词which/whom时，可以转换成关系代词which/whom/who+。。。+介词prep。的结构。但是有些情况下是不能做上述的转换的，如：1）当which/who(m)作由动词与介词构成意义完整的、不可分离的短语动词（注意：不是动词短语）（如果不知道什么是短语动词，可参考牛津高阶双解词典）的宾语时，介词不能前置。e。g。: This is the key which you are looking for。 (correct) This is the key for which you are looking。 (wrong)2）当省略了作介词宾语的关系代词which/who(m)时，介词不能前置。e。g。: I have the book you are talking about。 (correct) I have the book about you are talking。 (wrong)。
热心网友
Look after时固定短语。因此after不能前移。所以A是不对的
热心网友
当after 放 前时只能用whom．介词前置时只能用whom
热心网友
当whom引导定语从句时，介词一般都放在从句的句末。所以此句选择C是正确的。