I could suffocate you could suffocate he could suffocate we could suffocate you could suffocate they could suffocate
V-ing form
I could be suffocating you could be suffocating he could be suffocating we could be suffocating you could be suffocating they could be suffocating
Perfect
I could have suffocated you could have suffocated he could have suffocated we could have suffocated you could have suffocated they could have suffocated
V-ing perfect
I could have been suffocating you could have been suffocating he could have been suffocating we could have been suffocating you could have been suffocating they could have been suffocating
Negation
Simple form
I could not suffocate you could not suffocate he could not suffocate we could not suffocate you could not suffocate they could not suffocate
V-ing form
I could not be suffocating you could not be suffocating he could not be suffocating we could not be suffocating you could not be suffocating they could not be suffocating
Perfect
I could not have suffocated you could not have suffocated he could not have suffocated we could not have suffocated you could not have suffocated they could not have suffocated
V-ing perfect
I could not have been suffocating you could not have been suffocating he could not have been suffocating we could not have been suffocating you could not have been suffocating they could not have been suffocating
Interrogative form
Simple form
could I suffocate? could you suffocate? could he suffocate? could we suffocate? could you suffocate? could they suffocate?
V-ing form
could I be suffocating? could you be suffocating? could he be suffocating? could we be suffocating? could you be suffocating? could they be suffocating?
Perfect
could I have suffocated? could you have suffocated? could he have suffocated? could we have suffocated? could you have suffocated? could they have suffocated?
V-ing perfect
could I have been suffocating? could you have been suffocating? could he have been suffocating? could we have been suffocating? could you have been suffocating? could they have been suffocating?
Interro-negative form
Simple form
could I not suffocate? could you not suffocate? could he not suffocate? could we not suffocate? could you not suffocate? could they not suffocate?
V-ing form
could I not be suffocating? could you not be suffocating? could he not be suffocating? could we not be suffocating? could you not be suffocating? could they not be suffocating?
Perfect
could I not have suffocated? could you not have suffocated? could he not have suffocated? could we not have suffocated? could you not have suffocated? could they not have suffocated?
V-ing perfect
could I not have been suffocating? could you not have been suffocating? could he not have been suffocating? could we not have been suffocating? could you not have been suffocating? could they not have been suffocating?