could sailplane
Regular verb: sailplane - sailplaned- sailplaned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could sailplane
you could sailplane
he could sailplane
we could sailplane
you could sailplane
they could sailplane 	I could be sailplaning
you could be sailplaning
he could be sailplaning
we could be sailplaning
you could be sailplaning
they could be sailplaning	I could have sailplaned
you could have sailplaned
he could have sailplaned
we could have sailplaned
you could have sailplaned
they could have sailplaned	I could have been sailplaning
you could have been sailplaning
he could have been sailplaning
we could have been sailplaning
you could have been sailplaning
they could have been sailplaning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't sailplane
you couldn't sailplane
he couldn't sailplane
we couldn't sailplane
you couldn't sailplane
they couldn't sailplane 	I couldn't be sailplaning
you couldn't be sailplaning
he couldn't be sailplaning
we couldn't be sailplaning
you couldn't be sailplaning
they couldn't be sailplaning	I couldn't have sailplaned
you couldn't have sailplaned
he couldn't have sailplaned
we couldn't have sailplaned
you couldn't have sailplaned
they couldn't have sailplaned	I couldn't have been sailplaning
you couldn't have been sailplaning
he couldn't have been sailplaning
we couldn't have been sailplaning
you couldn't have been sailplaning
they couldn't have been sailplaning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I sailplane?
could you sailplane?
could he sailplane?
could we sailplane?
could you sailplane?
could they sailplane? 	could I be sailplaning?
could you be sailplaning?
could he be sailplaning?
could we be sailplaning?
could you be sailplaning?
could they be sailplaning? 	could I have sailplaned?
could you have sailplaned?
could he have sailplaned?
could we have sailplaned?
could you have sailplaned?
could they have sailplaned? 	could I have been sailplaning?
could you have been sailplaning?
could he have been sailplaning?
could we have been sailplaning?
could you have been sailplaning?
could they have been sailplaning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I sailplane?
couldn't you sailplane?
couldn't he sailplane?
couldn't we sailplane?
couldn't you sailplane?
couldn't they sailplane? 	couldn't I be sailplaning?
couldn't you be sailplaning?
couldn't he be sailplaning?
couldn't we be sailplaning?
couldn't you be sailplaning?
couldn't they be sailplaning? 	couldn't I have sailplaned?
couldn't you have sailplaned?
couldn't he have sailplaned?
couldn't we have sailplaned?
couldn't you have sailplaned?
couldn't they have sailplaned? 	couldn't I have been sailplaning?
couldn't you have been sailplaning?
couldn't he have been sailplaning?
couldn't we have been sailplaning?
couldn't you have been sailplaning?
couldn't they have been sailplaning?