I could tough you could tough she could tough we could tough you could tough they could tough
V-ing form
I could be toughing you could be toughing she could be toughing we could be toughing you could be toughing they could be toughing
Perfect
I could have toughed you could have toughed she could have toughed we could have toughed you could have toughed they could have toughed
V-ing perfect
I could have been toughing you could have been toughing she could have been toughing we could have been toughing you could have been toughing they could have been toughing
Negation
Simple form
I couldn't tough you couldn't tough she couldn't tough we couldn't tough you couldn't tough they couldn't tough
V-ing form
I couldn't be toughing you couldn't be toughing she couldn't be toughing we couldn't be toughing you couldn't be toughing they couldn't be toughing
Perfect
I couldn't have toughed you couldn't have toughed she couldn't have toughed we couldn't have toughed you couldn't have toughed they couldn't have toughed
V-ing perfect
I couldn't have been toughing you couldn't have been toughing she couldn't have been toughing we couldn't have been toughing you couldn't have been toughing they couldn't have been toughing
Interrogative form
Simple form
could I tough? could you tough? could she tough? could we tough? could you tough? could they tough?
V-ing form
could I be toughing? could you be toughing? could she be toughing? could we be toughing? could you be toughing? could they be toughing?
Perfect
could I have toughed? could you have toughed? could she have toughed? could we have toughed? could you have toughed? could they have toughed?
V-ing perfect
could I have been toughing? could you have been toughing? could she have been toughing? could we have been toughing? could you have been toughing? could they have been toughing?
Interro-negative form
Simple form
couldn't I tough? couldn't you tough? couldn't she tough? couldn't we tough? couldn't you tough? couldn't they tough?
V-ing form
couldn't I be toughing? couldn't you be toughing? couldn't she be toughing? couldn't we be toughing? couldn't you be toughing? couldn't they be toughing?
Perfect
couldn't I have toughed? couldn't you have toughed? couldn't she have toughed? couldn't we have toughed? couldn't you have toughed? couldn't they have toughed?
V-ing perfect
couldn't I have been toughing? couldn't you have been toughing? couldn't she have been toughing? couldn't we have been toughing? couldn't you have been toughing? couldn't they have been toughing?