could japan
Regular verb: japan - japaned- japaned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could japan
you could japan
he could japan
we could japan
you could japan
they could japan 	I could be japaning
you could be japaning
he could be japaning
we could be japaning
you could be japaning
they could be japaning	I could have japaned
you could have japaned
he could have japaned
we could have japaned
you could have japaned
they could have japaned	I could have been japaning
you could have been japaning
he could have been japaning
we could have been japaning
you could have been japaning
they could have been japaning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not japan
you could not japan
he could not japan
we could not japan
you could not japan
they could not japan 	I could not be japaning
you could not be japaning
he could not be japaning
we could not be japaning
you could not be japaning
they could not be japaning	I could not have japaned
you could not have japaned
he could not have japaned
we could not have japaned
you could not have japaned
they could not have japaned	I could not have been japaning
you could not have been japaning
he could not have been japaning
we could not have been japaning
you could not have been japaning
they could not have been japaning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I japan?
could you japan?
could he japan?
could we japan?
could you japan?
could they japan? 	could I be japaning?
could you be japaning?
could he be japaning?
could we be japaning?
could you be japaning?
could they be japaning? 	could I have japaned?
could you have japaned?
could he have japaned?
could we have japaned?
could you have japaned?
could they have japaned? 	could I have been japaning?
could you have been japaning?
could he have been japaning?
could we have been japaning?
could you have been japaning?
could they have been japaning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not japan?
could you not japan?
could he not japan?
could we not japan?
could you not japan?
could they not japan? 	could I not be japaning?
could you not be japaning?
could he not be japaning?
could we not be japaning?
could you not be japaning?
could they not be japaning? 	could I not have japaned?
could you not have japaned?
could he not have japaned?
could we not have japaned?
could you not have japaned?
could they not have japaned? 	could I not have been japaning?
could you not have been japaning?
could he not have been japaning?
could we not have been japaning?
could you not have been japaning?
could they not have been japaning?