could back
Regular verb: back - backed- backed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could back
you could back
she could back
we could back
you could back
they could back 	I could be backing
you could be backing
she could be backing
we could be backing
you could be backing
they could be backing	I could have backed
you could have backed
she 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
she could have been backing
we could have been backing
you could have been backing
they could have been backing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't back
you couldn't back
she 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
she 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
she 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
she couldn't have been backing
we couldn't have been backing
you couldn't have been backing
they couldn't have been backing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I back?
could you back?
could she back?
could we back?
could you back?
could they back? 	could I be backing?
could you be backing?
could she be backing?
could we be backing?
could you be backing?
could they be backing? 	could I have backed?
could you have backed?
could she 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 she have been backing?
could we have been backing?
could you have been backing?
could they have been backing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I back?
couldn't you back?
couldn't she 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 she 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 she 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 she have been backing?
couldn't we have been backing?
couldn't you have been backing?
couldn't they have been backing?