could trail
Verbo regular: trail - trailed- trailed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could trail
you could trail
he could trail
we could trail
you could trail
they could trail 	I could be trailing
you could be trailing
he could be trailing
we could be trailing
you could be trailing
they could be trailing	I could have trailed
you could have trailed
he could have trailed
we could have trailed
you could have trailed
they could have trailed	I could have been trailing
you could have been trailing
he could have been trailing
we could have been trailing
you could have been trailing
they could have been trailing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't trail
you couldn't trail
he couldn't trail
we couldn't trail
you couldn't trail
they couldn't trail 	I couldn't be trailing
you couldn't be trailing
he couldn't be trailing
we couldn't be trailing
you couldn't be trailing
they couldn't be trailing	I couldn't have trailed
you couldn't have trailed
he couldn't have trailed
we couldn't have trailed
you couldn't have trailed
they couldn't have trailed	I couldn't have been trailing
you couldn't have been trailing
he couldn't have been trailing
we couldn't have been trailing
you couldn't have been trailing
they couldn't have been trailing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I trail?
could you trail?
could he trail?
could we trail?
could you trail?
could they trail? 	could I be trailing?
could you be trailing?
could he be trailing?
could we be trailing?
could you be trailing?
could they be trailing? 	could I have trailed?
could you have trailed?
could he have trailed?
could we have trailed?
could you have trailed?
could they have trailed? 	could I have been trailing?
could you have been trailing?
could he have been trailing?
could we have been trailing?
could you have been trailing?
could they have been trailing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I trail?
couldn't you trail?
couldn't he trail?
couldn't we trail?
couldn't you trail?
couldn't they trail? 	couldn't I be trailing?
couldn't you be trailing?
couldn't he be trailing?
couldn't we be trailing?
couldn't you be trailing?
couldn't they be trailing? 	couldn't I have trailed?
couldn't you have trailed?
couldn't he have trailed?
couldn't we have trailed?
couldn't you have trailed?
couldn't they have trailed? 	couldn't I have been trailing?
couldn't you have been trailing?
couldn't he have been trailing?
couldn't we have been trailing?
couldn't you have been trailing?
couldn't they have been trailing?