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