为什么用slip?shopping bag ladies又是什么?

slip 的过去式用slip bank slip 是什么 Slip rings 是什么 It is___a shopping bag ___a bag of shopping is this shopping bag yours? do you need shopping bag? slip what kind of bag does Lily often use for shopping?为什么kind不加s slip slop slap意思是什么 He went shopping with his mother. 为什么要用shopping slip的过去式和过去分词是什么? go shopping中的shopping是动名词对吧,但是go不是不及物动词的吗,后面为什么又加动名词呢?