Had already produced the high quality steel in the 12th century B.C., Produced the plain tool steel of carbon in the 7th century B.C.是什么意思_Had already produced the high quality steel in the 12th century B.C., Produced the plain tool steel of carbon in the 7th century B.C.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句