根据对话选词填空。

had better not , needn’t, had better, would rather, mustn’t

JENNY: Nick, we 1______ go to bed. It’s very late.
NICK: I know, but I 2______ help Trig than go to bed. He’s tearing up his English exercise book and he’s throwing his grammar book round the room. I don’t think he’s very happy.
JENNY: Well, you 3______ stay up too long.
NICK: Trig, stop it. You 4______ throw your books at the wall. It won’t help and you might break something. You 5______ work at your English now. What are you learning?
TRIG: Abbreviation [n] 1 U abbreviating, being abbreviated 2 C shortened form of a word, phrase, etc. ‘Sept’ an abbreviation for ‘September’…
NICK: But Trig, that’s from the dictionary. You 6______ learn the whole dictionary by heart!