（）是为了消除现存的不合格的原因或不合乎需求的偏离以预防再次发生而采取的措施。
参考答案：纠正措施
---Can you go shopping with me tomorrow?
---Sorry. I have to _____ my sick mother at home..
A．pay for
B．look for
C．go for
D．care for
桩核冠的根尖封闭不少于（）
A.4mm
B.2mm
C.1.5mm
D.1mm
E.3mm
