i made a mistake, fortunately found it promptly, then i told my boss;  he answered me it's not big problem, it just only needed to be reinjected the oil to change the color; after listening to such words, i felt warm; maybe some bosses would reprimand the stuff once meeting such question.

      i am lucky! i should do my utmost to make the work better. yesterday is history, tomorrow is mystery, today is gift. learn from one friend. Struggle!