That is because many of the men who worked to gather substances from trees wore no shoes.They would make turpentine from tar and get the black, sticky tar on the heels of their feet.

• 因为许多从棕榈树上采集焦油的人都打着赤脚，他们要从焦油中提取松节油，所以，他们的脚后跟就涂上了黑兮兮、粘糊糊的焦油。