单项选择题
To anneal a copper gasket, you should heat the gasket（）
A.and quench it in oil B.cherry red and quench in water C.and let it cool slowly in the air D.and carbonize
单项选择题 A drilled hole is accurately finished to size with a （）
单项选择题 Which of the files listed is tapered on three sides and is used to file acute internal angles?（）
单项选择题 Using a file without a handle may result in （）
