I could tag you could tag he could tag we could tag you could tag they could tag
V-ing form
I could be tagging you could be tagging he could be tagging we could be tagging you could be tagging they could be tagging
Perfect
I could have tagged you could have tagged he could have tagged we could have tagged you could have tagged they could have tagged
V-ing perfect
I could have been tagging you could have been tagging he could have been tagging we could have been tagging you could have been tagging they could have been tagging
Negation
Simple form
I couldn't tag you couldn't tag he couldn't tag we couldn't tag you couldn't tag they couldn't tag
V-ing form
I couldn't be tagging you couldn't be tagging he couldn't be tagging we couldn't be tagging you couldn't be tagging they couldn't be tagging
Perfect
I couldn't have tagged you couldn't have tagged he couldn't have tagged we couldn't have tagged you couldn't have tagged they couldn't have tagged
V-ing perfect
I couldn't have been tagging you couldn't have been tagging he couldn't have been tagging we couldn't have been tagging you couldn't have been tagging they couldn't have been tagging
Interrogative form
Simple form
could I tag? could you tag? could he tag? could we tag? could you tag? could they tag?
V-ing form
could I be tagging? could you be tagging? could he be tagging? could we be tagging? could you be tagging? could they be tagging?
Perfect
could I have tagged? could you have tagged? could he have tagged? could we have tagged? could you have tagged? could they have tagged?
V-ing perfect
could I have been tagging? could you have been tagging? could he have been tagging? could we have been tagging? could you have been tagging? could they have been tagging?
Interro-negative form
Simple form
couldn't I tag? couldn't you tag? couldn't he tag? couldn't we tag? couldn't you tag? couldn't they tag?
V-ing form
couldn't I be tagging? couldn't you be tagging? couldn't he be tagging? couldn't we be tagging? couldn't you be tagging? couldn't they be tagging?
Perfect
couldn't I have tagged? couldn't you have tagged? couldn't he have tagged? couldn't we have tagged? couldn't you have tagged? couldn't they have tagged?
V-ing perfect
couldn't I have been tagging? couldn't you have been tagging? couldn't he have been tagging? couldn't we have been tagging? couldn't you have been tagging? couldn't they have been tagging?