Product quality is graded by exterior and interior specification. 產品質量實行分等制，根據外觀質量定等和內在質量評等二者結合定等。
Testing purpose also changed gradually from controlling appearance quality to an important method of insuring further processing. 測試的目的也發生了變化逐步從外觀質量控制的一個重要方法，確保進一步處理。
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