Lesson 1 Introduction

所屬欄目:合成革專(zhuān)業(yè)英語(yǔ)

Coating,bonding and sealing are techniques that humankind has used for many thousands ofyears. For a long time,only natural resins,oils and fats were used for these purposes.Shellac,a natural resin secreted by the scaly lac insect,has been used in India f ......(本文共 5303 字 )     [閱讀本文] >>


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