4．
根据课文内容，填上一个适当的词，完成短文。(首字母已给出)
Lu Ban was a c. One day a leaf cut his f. He looked at the leaf c. There were many t on the leaf and the teeth were s. So he made a t with teeth like these. It c cut things. It was a s. It was the first one in the world. People are still u this tool today.
