(of the way in which something is chewed) with a crunch / (of the way in which something is chewed) in a crunching manner / (of the way in which something is chewed) in a gnawing manner / (of the way in which something is chewed) in a munching manner

chew *something in a gnawing manner / chew *something in a munching manner / chew *something in a crunching manner

in a scratching manner / in a scratchy manner

scratch (the head)

(of the way in which one scratches him or herself) with a rasping sound / (of the way in which one scratches him or herself) with a scratching sound

scratch oneself with a scratching sound / scratch oneself with a rasping sound

(of the way one studies) in a grinding way / (of the way one studies) in a drudging way / really hit the books

trudge along (in *one's studies) / (study) go the grind / hit the book

(of the way in which one attends to his/her studies) grindingly / (of the way in which one attends to his/her studies) drudgingly

study grindingly / study drudgingly / <c:figurative> go back to the grind