I'd be understanding you'd be understanding she'd be understanding we'd be understanding you'd be understanding they'd be understanding
Perfect
I should've understood you should've understood she should've understood we should've understood you should've understood they should've understood
V-ing perfect
I should've been understanding you should've been understanding she should've been understanding we should've been understanding you should've been understanding they should've been understanding
Negation
Simple form
I shouldn't understand you shouldn't understand she shouldn't understand we shouldn't understand you shouldn't understand they shouldn't understand
V-ing form
I shouldn't be understanding you shouldn't be understanding she shouldn't be understanding we shouldn't be understanding you shouldn't be understanding they shouldn't be understanding
Perfect
I shouldn't have understood you shouldn't have understood she shouldn't have understood we shouldn't have understood you shouldn't have understood they shouldn't have understood
V-ing perfect
I shouldn't have been understanding you shouldn't have been understanding she shouldn't have been understanding we shouldn't have been understanding you shouldn't have been understanding they shouldn't have been understanding
Interrogative form
Simple form
should I understand? should you understand? should she understand? should we understand? should you understand? should they understand?
V-ing form
should I be understanding? should you be understanding? should she be understanding? should we be understanding? should you be understanding? should they be understanding?
Perfect
should I have understood? should you have understood? should she have understood? should we have understood? should you have understood? should they have understood?
V-ing perfect
should I have been understanding? should you have been understanding? should she have been understanding? should we have been understanding? should you have been understanding? should they have been understanding?
Interro-negative form
Simple form
shouldn't I understand? shouldn't you understand? shouldn't she understand? shouldn't we understand? shouldn't you understand? shouldn't they understand?
V-ing form
shouldn't I be understanding? shouldn't you be understanding? shouldn't she be understanding? shouldn't we be understanding? shouldn't you be understanding? shouldn't they be understanding?
Perfect
shouldn't I have understood? shouldn't you have understood? shouldn't she have understood? shouldn't we have understood? shouldn't you have understood? shouldn't they have understood?
V-ing perfect
shouldn't I have been understanding? shouldn't you have been understanding? shouldn't she have been understanding? shouldn't we have been understanding? shouldn't you have been understanding? shouldn't they have been understanding?