An informal drawing or message on a public wall or surface, often done without permission.
The old wall was covered in graffito from people passing by.
那面旧墙被路过的人涂鸦覆盖了。
Artwork made by scratching a design into a surface to show the layer underneath.
The graffito on the metal plate was created by scratching away the top layer.
金属板上的涂鸦是通过刮掉顶层来创作的。