could subtitle
Regular verb: subtitle - subtitled- subtitled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could subtitle
you could subtitle
she could subtitle
we could subtitle
you could subtitle
they could subtitle 	I could be subtitling
you could be subtitling
she could be subtitling
we could be subtitling
you could be subtitling
they could be subtitling	I could have subtitled
you could have subtitled
she could have subtitled
we could have subtitled
you could have subtitled
they could have subtitled	I could have been subtitling
you could have been subtitling
she could have been subtitling
we could have been subtitling
you could have been subtitling
they could have been subtitling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't subtitle
you couldn't subtitle
she couldn't subtitle
we couldn't subtitle
you couldn't subtitle
they couldn't subtitle 	I couldn't be subtitling
you couldn't be subtitling
she couldn't be subtitling
we couldn't be subtitling
you couldn't be subtitling
they couldn't be subtitling	I couldn't have subtitled
you couldn't have subtitled
she couldn't have subtitled
we couldn't have subtitled
you couldn't have subtitled
they couldn't have subtitled	I couldn't have been subtitling
you couldn't have been subtitling
she couldn't have been subtitling
we couldn't have been subtitling
you couldn't have been subtitling
they couldn't have been subtitling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I subtitle?
could you subtitle?
could she subtitle?
could we subtitle?
could you subtitle?
could they subtitle? 	could I be subtitling?
could you be subtitling?
could she be subtitling?
could we be subtitling?
could you be subtitling?
could they be subtitling? 	could I have subtitled?
could you have subtitled?
could she have subtitled?
could we have subtitled?
could you have subtitled?
could they have subtitled? 	could I have been subtitling?
could you have been subtitling?
could she have been subtitling?
could we have been subtitling?
could you have been subtitling?
could they have been subtitling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I subtitle?
couldn't you subtitle?
couldn't she subtitle?
couldn't we subtitle?
couldn't you subtitle?
couldn't they subtitle? 	couldn't I be subtitling?
couldn't you be subtitling?
couldn't she be subtitling?
couldn't we be subtitling?
couldn't you be subtitling?
couldn't they be subtitling? 	couldn't I have subtitled?
couldn't you have subtitled?
couldn't she have subtitled?
couldn't we have subtitled?
couldn't you have subtitled?
couldn't they have subtitled? 	couldn't I have been subtitling?
couldn't you have been subtitling?
couldn't she have been subtitling?
couldn't we have been subtitling?
couldn't you have been subtitling?
couldn't they have been subtitling?