制造厂首次采用的钢材和焊接材料必须进行评定,在同一制造厂已评定并批准的工艺,可不再评定;遇有哪些情况者,应重新进行评定:( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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