SHOULD


Meaning of SHOULD in English

(REASON) [auxiliary verb] [+ infinitive without to] he/she/it should - used after 'why' when giving or asking the reason for somethingWhy should anyone want to eat something so horrible?Why shouldn't she buy it if she can afford it?Why should he have said it if he didn't mean it?

Cambridge English vocab.      Кембриджский английский словарь.