could back
Verbo regular: back - backed- backed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could back
you could back
he could back
we could back
you could back
they could back 	I could be backing
you could be backing
he could be backing
we could be backing
you could be backing
they could be backing	I could have backed
you could have backed
he could have backed
we could have backed
you could have backed
they could have backed	I could have been backing
you could have been backing
he could have been backing
we could have been backing
you could have been backing
they could have been backing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't back
you couldn't back
he couldn't back
we couldn't back
you couldn't back
they couldn't back 	I couldn't be backing
you couldn't be backing
he couldn't be backing
we couldn't be backing
you couldn't be backing
they couldn't be backing	I couldn't have backed
you couldn't have backed
he couldn't have backed
we couldn't have backed
you couldn't have backed
they couldn't have backed	I couldn't have been backing
you couldn't have been backing
he couldn't have been backing
we couldn't have been backing
you couldn't have been backing
they couldn't have been backing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I back?
could you back?
could he back?
could we back?
could you back?
could they back? 	could I be backing?
could you be backing?
could he be backing?
could we be backing?
could you be backing?
could they be backing? 	could I have backed?
could you have backed?
could he have backed?
could we have backed?
could you have backed?
could they have backed? 	could I have been backing?
could you have been backing?
could he have been backing?
could we have been backing?
could you have been backing?
could they have been backing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I back?
couldn't you back?
couldn't he back?
couldn't we back?
couldn't you back?
couldn't they back? 	couldn't I be backing?
couldn't you be backing?
couldn't he be backing?
couldn't we be backing?
couldn't you be backing?
couldn't they be backing? 	couldn't I have backed?
couldn't you have backed?
couldn't he have backed?
couldn't we have backed?
couldn't you have backed?
couldn't they have backed? 	couldn't I have been backing?
couldn't you have been backing?
couldn't he have been backing?
couldn't we have been backing?
couldn't you have been backing?
couldn't they have been backing?