(来学网)X线诊断机房的副防护应有的铅当量是
  • A.
    (来学网)4mmPb
  • B.
    (来学网)3mmPb
  • C.
    (来学网)2mmPb
  • D.
    (来学网)1mmPb
  • E.
    (来学网)0.5mmPb