单选题 What the doctors really doubt is ______ my mother will recover from the serious disease soon.
  • A.when
  • B.how
  • C.whether
  • D.what
【正确答案】 C
【答案解析】[解析] What the doctors really doubt是主语从句，is后是一个表语从句。根据题意及doubt的特点，C是最佳选项。