scrape 和scratch怎样区别?

scratch ------ 用耙子或手爪抓
1）to rub your skin with your nails because it feels uncomfortable
2）to cut someone's skin slightly with your nails or with something sharp
【例句】
you scratch my back,I'll scratch yours
That cat scratches.
那只猫会抓伤人.
The famine is so bad,aid can only scratch the surface.
饥荒十分严重,援助也只是杯水车薪.
scrape ---------檫去、用刀刮、挖出
1）to remove something from a surface using the edge of a knife,a stick etc
2）to make a noise by rubbing roughly against a surface
【例句】
Scrape your shoes on the door mat before you come in.
进屋前先在门口擦鞋垫上擦一擦鞋子.
He suffered a few cuts and scrapes.
他割破和擦伤了几个地方.