1) You shouldn't have treated him shabbily.
你不该亏待他。
2) You wronged him.
你对待他不公平。
3) You mustn't...!
你不应该……！
4) You should not go Back on your word.
你不该食言。
5) It ill beseems you to refuse.
你不该拒绝。
6) You originally should thank him.
你本该谢谢他。
参考词条