I could lean you could lean he could lean we could lean you could lean they could lean
V-ing form
I could be leaning you could be leaning he could be leaning we could be leaning you could be leaning they could be leaning
Perfect
I could have leaned you could have leaned he could have leaned we could have leaned you could have leaned they could have leaned
V-ing perfect
I could have been leaning you could have been leaning he could have been leaning we could have been leaning you could have been leaning they could have been leaning
Negation
Simple form
I could not lean you could not lean he could not lean we could not lean you could not lean they could not lean
V-ing form
I could not be leaning you could not be leaning he could not be leaning we could not be leaning you could not be leaning they could not be leaning
Perfect
I could not have leaned you could not have leaned he could not have leaned we could not have leaned you could not have leaned they could not have leaned
V-ing perfect
I could not have been leaning you could not have been leaning he could not have been leaning we could not have been leaning you could not have been leaning they could not have been leaning
Interrogative form
Simple form
could I lean? could you lean? could he lean? could we lean? could you lean? could they lean?
V-ing form
could I be leaning? could you be leaning? could he be leaning? could we be leaning? could you be leaning? could they be leaning?
Perfect
could I have leaned? could you have leaned? could he have leaned? could we have leaned? could you have leaned? could they have leaned?
V-ing perfect
could I have been leaning? could you have been leaning? could he have been leaning? could we have been leaning? could you have been leaning? could they have been leaning?
Interro-negative form
Simple form
could I not lean? could you not lean? could he not lean? could we not lean? could you not lean? could they not lean?
V-ing form
could I not be leaning? could you not be leaning? could he not be leaning? could we not be leaning? could you not be leaning? could they not be leaning?
Perfect
could I not have leaned? could you not have leaned? could he not have leaned? could we not have leaned? could you not have leaned? could they not have leaned?
V-ing perfect
could I not have been leaning? could you not have been leaning? could he not have been leaning? could we not have been leaning? could you not have been leaning? could they not have been leaning?