Just as there are many things to know about a word - its spoken form, its written form, its inflected and derived forms, its collocations and so on - there are degrees of knowing.

• 学习一个单词要掌握他多方面的知识，如它的口语形式及书面形式，曲折及派生形式，或词语搭配，同样掌握这些知识也有程度上大的差异，其中被人们广泛接受的知识程度的划分就是接受型词汇和产出型词汇。