(来学网)有效焦点大于多少,透视时X线管阳极可不转动
  • A.
    (来学网)0.01
  • B.
    (来学网)0.3
  • C.
    (来学网)0.05
  • D.
    (来学网)0.1
  • E.
    (来学网)0.2