Pencil ... acting a scribble on a sheet of paper.The eraser ... acting delete everything crayon scribble mistakeSometimes both pencil and Eraser may be frustrated that nuisance must depend on each other.
Pencil... Do write down on a piece of paper eraser... Do erase everything pencils do make a mistake, and sometimes the pencil and eraser can be frustrating gripe to rely on each other.