a three-layer dressing incorporating chitosana fiber derived from crab shells,350 million pounds of which are discarded in the U.S. annually是什么意思_a three-layer dressing incorporating chitosana fiber derived from crab shells,350 million pounds of which are discarded in the U.S. annually在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句