I could land you could land she could land we could land you could land they could land
V-ing form
I could be landing you could be landing she could be landing we could be landing you could be landing they could be landing
Perfect
I could have landed you could have landed she could have landed we could have landed you could have landed they could have landed
V-ing perfect
I could have been landing you could have been landing she could have been landing we could have been landing you could have been landing they could have been landing
Negation
Simple form
I could not land you could not land she could not land we could not land you could not land they could not land
V-ing form
I could not be landing you could not be landing she could not be landing we could not be landing you could not be landing they could not be landing
Perfect
I could not have landed you could not have landed she could not have landed we could not have landed you could not have landed they could not have landed
V-ing perfect
I could not have been landing you could not have been landing she could not have been landing we could not have been landing you could not have been landing they could not have been landing
Interrogative form
Simple form
could I land? could you land? could she land? could we land? could you land? could they land?
V-ing form
could I be landing? could you be landing? could she be landing? could we be landing? could you be landing? could they be landing?
Perfect
could I have landed? could you have landed? could she have landed? could we have landed? could you have landed? could they have landed?
V-ing perfect
could I have been landing? could you have been landing? could she have been landing? could we have been landing? could you have been landing? could they have been landing?
Interro-negative form
Simple form
could I not land? could you not land? could she not land? could we not land? could you not land? could they not land?
V-ing form
could I not be landing? could you not be landing? could she not be landing? could we not be landing? could you not be landing? could they not be landing?
Perfect
could I not have landed? could you not have landed? could she not have landed? could we not have landed? could you not have landed? could they not have landed?
V-ing perfect
could I not have been landing? could you not have been landing? could she not have been landing? could we not have been landing? could you not have been landing? could they not have been landing?