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