A membranous structure in a hollow organ or passage,as in an artery or a vein,that folds or closes to prevent the return flow of the body fluid passing through it.是什么意思_A membranous structure in a hollow organ or passage,as in an artery or a vein,that folds or closes to prevent the return flow of the body fluid passing through it.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句