(来学网)血中还原血红蛋白超过多少时皮肤黏膜可出现发绀( )
  • A.
    (来学网)50g/L
  • B.
    (来学网)55g/L
  • C.
    (来学网)60g/L
  • D.
    (来学网)65g/L
  • E.
    (来学网)70g/L