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