怎樣祛除骨頭湯上層的灰色泡沫?

zhugutoutangdeshihou，yaoxianyongkaishuibagutouzhuyixia，mudeshibagutoulidexueshuizhuchulai。zaiyongqingshuigutouchongxiyixia。zuihoucaishifangzuoliaohegutouyiqiaotang，shunbiandianliangdicu。zheyangjiumeidexuepaopaole。zuoqitatang（排骨
、雞等）的時候也要這樣做一遍才行。