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