I could perforate you could perforate he could perforate we could perforate you could perforate they could perforate
V-ing form
I could be perforating you could be perforating he could be perforating we could be perforating you could be perforating they could be perforating
Perfect
I could have perforated you could have perforated he could have perforated we could have perforated you could have perforated they could have perforated
V-ing perfect
I could have been perforating you could have been perforating he could have been perforating we could have been perforating you could have been perforating they could have been perforating
Negation
Simple form
I couldn't perforate you couldn't perforate he couldn't perforate we couldn't perforate you couldn't perforate they couldn't perforate
V-ing form
I couldn't be perforating you couldn't be perforating he couldn't be perforating we couldn't be perforating you couldn't be perforating they couldn't be perforating
Perfect
I couldn't have perforated you couldn't have perforated he couldn't have perforated we couldn't have perforated you couldn't have perforated they couldn't have perforated
V-ing perfect
I couldn't have been perforating you couldn't have been perforating he couldn't have been perforating we couldn't have been perforating you couldn't have been perforating they couldn't have been perforating
Interrogative form
Simple form
could I perforate? could you perforate? could he perforate? could we perforate? could you perforate? could they perforate?
V-ing form
could I be perforating? could you be perforating? could he be perforating? could we be perforating? could you be perforating? could they be perforating?
Perfect
could I have perforated? could you have perforated? could he have perforated? could we have perforated? could you have perforated? could they have perforated?
V-ing perfect
could I have been perforating? could you have been perforating? could he have been perforating? could we have been perforating? could you have been perforating? could they have been perforating?
Interro-negative form
Simple form
couldn't I perforate? couldn't you perforate? couldn't he perforate? couldn't we perforate? couldn't you perforate? couldn't they perforate?
V-ing form
couldn't I be perforating? couldn't you be perforating? couldn't he be perforating? couldn't we be perforating? couldn't you be perforating? couldn't they be perforating?
Perfect
couldn't I have perforated? couldn't you have perforated? couldn't he have perforated? couldn't we have perforated? couldn't you have perforated? couldn't they have perforated?
V-ing perfect
couldn't I have been perforating? couldn't you have been perforating? couldn't he have been perforating? couldn't we have been perforating? couldn't you have been perforating? couldn't they have been perforating?