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