We use continuous tenses only for actions and happenings (they are eating / it is raining etc.). Some verbs (for example, know and like) are not action verbs. You cannot say 'I'm knowing' or 'they are liking'. you can only say 'I know' , 'they like'. The following verbs are not normally used in continuous tense: like love hate want need perfer know realise suppose mean understatnd believe rememb..