I could plane you could plane he could plane we could plane you could plane they could plane
V-ing form
I could be planing you could be planing he could be planing we could be planing you could be planing they could be planing
Perfect
I could have planed you could have planed he could have planed we could have planed you could have planed they could have planed
V-ing perfect
I could have been planing you could have been planing he could have been planing we could have been planing you could have been planing they could have been planing
Negation
Simple form
I could not plane you could not plane he could not plane we could not plane you could not plane they could not plane
V-ing form
I could not be planing you could not be planing he could not be planing we could not be planing you could not be planing they could not be planing
Perfect
I could not have planed you could not have planed he could not have planed we could not have planed you could not have planed they could not have planed
V-ing perfect
I could not have been planing you could not have been planing he could not have been planing we could not have been planing you could not have been planing they could not have been planing
Interrogative form
Simple form
could I plane? could you plane? could he plane? could we plane? could you plane? could they plane?
V-ing form
could I be planing? could you be planing? could he be planing? could we be planing? could you be planing? could they be planing?
Perfect
could I have planed? could you have planed? could he have planed? could we have planed? could you have planed? could they have planed?
V-ing perfect
could I have been planing? could you have been planing? could he have been planing? could we have been planing? could you have been planing? could they have been planing?
Interro-negative form
Simple form
could I not plane? could you not plane? could he not plane? could we not plane? could you not plane? could they not plane?
V-ing form
could I not be planing? could you not be planing? could he not be planing? could we not be planing? could you not be planing? could they not be planing?
Perfect
could I not have planed? could you not have planed? could he not have planed? could we not have planed? could you not have planed? could they not have planed?
V-ing perfect
could I not have been planing? could you not have been planing? could he not have been planing? could we not have been planing? could you not have been planing? could they not have been planing?