could trace
Regular verb: trace - traced- traced

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could trace
you could trace
she could trace
we could trace
you could trace
they could trace 	I could be tracing
you could be tracing
she could be tracing
we could be tracing
you could be tracing
they could be tracing	I could have traced
you could have traced
she could have traced
we could have traced
you could have traced
they could have traced	I could have been tracing
you could have been tracing
she could have been tracing
we could have been tracing
you could have been tracing
they could have been tracing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't trace
you couldn't trace
she couldn't trace
we couldn't trace
you couldn't trace
they couldn't trace 	I couldn't be tracing
you couldn't be tracing
she couldn't be tracing
we couldn't be tracing
you couldn't be tracing
they couldn't be tracing	I couldn't have traced
you couldn't have traced
she couldn't have traced
we couldn't have traced
you couldn't have traced
they couldn't have traced	I couldn't have been tracing
you couldn't have been tracing
she couldn't have been tracing
we couldn't have been tracing
you couldn't have been tracing
they couldn't have been tracing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I trace?
could you trace?
could she trace?
could we trace?
could you trace?
could they trace? 	could I be tracing?
could you be tracing?
could she be tracing?
could we be tracing?
could you be tracing?
could they be tracing? 	could I have traced?
could you have traced?
could she have traced?
could we have traced?
could you have traced?
could they have traced? 	could I have been tracing?
could you have been tracing?
could she have been tracing?
could we have been tracing?
could you have been tracing?
could they have been tracing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I trace?
couldn't you trace?
couldn't she trace?
couldn't we trace?
couldn't you trace?
couldn't they trace? 	couldn't I be tracing?
couldn't you be tracing?
couldn't she be tracing?
couldn't we be tracing?
couldn't you be tracing?
couldn't they be tracing? 	couldn't I have traced?
couldn't you have traced?
couldn't she have traced?
couldn't we have traced?
couldn't you have traced?
couldn't they have traced? 	couldn't I have been tracing?
couldn't you have been tracing?
couldn't she have been tracing?
couldn't we have been tracing?
couldn't you have been tracing?
couldn't they have been tracing?