I'd be treading you'd be treading he'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 he 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 he 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 he 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 he 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 he 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 he 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 he tread? should we tread? should you tread? should they tread?
V-ing form
should I be treading? should you be treading? should he 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 he 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 he 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 he 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 he 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 he 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 he have been treading? shouldn't we have been treading? shouldn't you have been treading? shouldn't they have been treading?