If the speaker selects the imperative mood, he assumes the role of one giving commands and puts the addressee in the role of one expected ot obey orders.
Sometimes in English, we use the verb to have in the imperative when someone's going to go do something and we want them to have a good time when they're doing it.
有时在英语中,我们在祈使语气中使用动词 to have 当某人要去做某事时,我们希望他们在做某事时玩得开心。