(来学网)窝沟封闭中酸蚀用磷酸浓度为
  • A.
    (来学网)20%~30%
  • B.
    (来学网)30%~40%
  • C.
    (来学网)40%~50%
  • D.
    (来学网)50%~60%
  • E.
    (来学网)60%~70%
正确答案:
B