Which of the following is false?（）
A company should develop a SMS and implement it
B. A company implementing a SMS properly may obtain a DOC
C. Once a company obtains its DOC, each vessel of this company will obtain a SMC
DOC is valid for 60 months unless “major non-conformity” is found
查看答案
超声加工主要适用各种（）加工。
A. 不导电的硬脆材料
B. 不导电的非金属材料
C. 导电的有色金属材料
D. 导电的黑色金属材料
GB2946-1992，其中GB代表工业标准。
A. 正确
B. 错误
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