つめを噛むんじゃない。

nail (e.g. fingernail, toenail); claw; talon; hoof; plectrum; pick; hook; clasp

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to bite; to chew; to gnaw; to crash against (e.g. of waves); to break onto (shore); to engage (of cogs, zippers, etc.); to mesh; to fit together; to be involved in; to fumble one's words (during a play, broadcast, etc.); to falter with one's words; to strongly confute; to argue down; to rebuke; to scold harshly

yes; yeah; uh huh; negative verb ending used in informal speech (abbr. of negative verb ending "nu"); abbr. of particle "no"; abbr. of particle "ni" (used especially when it precedes the verb "naru")

then; well; so; well then; combination of 'de' and 'wa' particles; plain copula