うそを言ってはいけないよ。

Eurasian bullfinch (Pyrrhula pyrrhula); Japanese bullfinch

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 say; to utter; to declare; to name; to call; to go (e.g. "the alarm went ping"); to make a noise

if ... then; when; and; why don't you...?; the more (one does something); because; since

indicates certainty, emphasis, contempt, request, etc.; used when calling out to someone; used to catch one's breath or get someone's attention; yo!