I'd be treading you'd be treading she'd be treading we'd be treading you'd be treading they'd be treading
Perfect
I should've trod, trodden you should've trod, trodden she should've trod, trodden we should've trod, trodden you should've trod, trodden they should've trod, trodden
V-ing perfect
I should've been treading you should've been treading she should've been treading we should've been treading you should've been treading they should've been treading
Negation
Simple form
I shouldn't tread you shouldn't tread she shouldn't tread we shouldn't tread you shouldn't tread they shouldn't tread
V-ing form
I shouldn't be treading you shouldn't be treading she shouldn't be treading we shouldn't be treading you shouldn't be treading they shouldn't be treading
Perfect
I shouldn't have trod, trodden you shouldn't have trod, trodden she shouldn't have trod, trodden we shouldn't have trod, trodden you shouldn't have trod, trodden they shouldn't have trod, trodden
V-ing perfect
I shouldn't have been treading you shouldn't have been treading she shouldn't have been treading we shouldn't have been treading you shouldn't have been treading they shouldn't have been treading
Interrogative form
Simple form
should I tread? should you tread? should she tread? should we tread? should you tread? should they tread?
V-ing form
should I be treading? should you be treading? should she be treading? should we be treading? should you be treading? should they be treading?
Perfect
should I have trod, trodden? should you have trod, trodden? should she have trod, trodden? should we have trod, trodden? should you have trod, trodden? should they have trod, trodden?
V-ing perfect
should I have been treading? should you have been treading? should she have been treading? should we have been treading? should you have been treading? should they have been treading?
Interro-negative form
Simple form
shouldn't I tread? shouldn't you tread? shouldn't she tread? shouldn't we tread? shouldn't you tread? shouldn't they tread?
V-ing form
shouldn't I be treading? shouldn't you be treading? shouldn't she be treading? shouldn't we be treading? shouldn't you be treading? shouldn't they be treading?
Perfect
shouldn't I have trod, trodden? shouldn't you have trod, trodden? shouldn't she have trod, trodden? shouldn't we have trod, trodden? shouldn't you have trod, trodden? shouldn't they have trod, trodden?
V-ing perfect
shouldn't I have been treading? shouldn't you have been treading? shouldn't she have been treading? shouldn't we have been treading? shouldn't you have been treading? shouldn't they have been treading?