could preboard
Regular verb: preboard - preboarded- preboarded

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could preboard
you could preboard
he could preboard
we could preboard
you could preboard
they could preboard 	I could be preboarding
you could be preboarding
he could be preboarding
we could be preboarding
you could be preboarding
they could be preboarding	I could have preboarded
you could have preboarded
he could have preboarded
we could have preboarded
you could have preboarded
they could have preboarded	I could have been preboarding
you could have been preboarding
he could have been preboarding
we could have been preboarding
you could have been preboarding
they could have been preboarding	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't preboard
you couldn't preboard
he couldn't preboard
we couldn't preboard
you couldn't preboard
they couldn't preboard 	I couldn't be preboarding
you couldn't be preboarding
he couldn't be preboarding
we couldn't be preboarding
you couldn't be preboarding
they couldn't be preboarding	I couldn't have preboarded
you couldn't have preboarded
he couldn't have preboarded
we couldn't have preboarded
you couldn't have preboarded
they couldn't have preboarded	I couldn't have been preboarding
you couldn't have been preboarding
he couldn't have been preboarding
we couldn't have been preboarding
you couldn't have been preboarding
they couldn't have been preboarding	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I preboard?
could you preboard?
could he preboard?
could we preboard?
could you preboard?
could they preboard? 	could I be preboarding?
could you be preboarding?
could he be preboarding?
could we be preboarding?
could you be preboarding?
could they be preboarding? 	could I have preboarded?
could you have preboarded?
could he have preboarded?
could we have preboarded?
could you have preboarded?
could they have preboarded? 	could I have been preboarding?
could you have been preboarding?
could he have been preboarding?
could we have been preboarding?
could you have been preboarding?
could they have been preboarding? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I preboard?
couldn't you preboard?
couldn't he preboard?
couldn't we preboard?
couldn't you preboard?
couldn't they preboard? 	couldn't I be preboarding?
couldn't you be preboarding?
couldn't he be preboarding?
couldn't we be preboarding?
couldn't you be preboarding?
couldn't they be preboarding? 	couldn't I have preboarded?
couldn't you have preboarded?
couldn't he have preboarded?
couldn't we have preboarded?
couldn't you have preboarded?
couldn't they have preboarded? 	couldn't I have been preboarding?
couldn't you have been preboarding?
couldn't he have been preboarding?
couldn't we have been preboarding?
couldn't you have been preboarding?
couldn't they have been preboarding?