I could derail you could derail she could derail we could derail you could derail they could derail
V-ing form
I could be derailing you could be derailing she could be derailing we could be derailing you could be derailing they could be derailing
Perfect
I could have derailed you could have derailed she could have derailed we could have derailed you could have derailed they could have derailed
V-ing perfect
I could have been derailing you could have been derailing she could have been derailing we could have been derailing you could have been derailing they could have been derailing
Negation
Simple form
I couldn't derail you couldn't derail she couldn't derail we couldn't derail you couldn't derail they couldn't derail
V-ing form
I couldn't be derailing you couldn't be derailing she couldn't be derailing we couldn't be derailing you couldn't be derailing they couldn't be derailing
Perfect
I couldn't have derailed you couldn't have derailed she couldn't have derailed we couldn't have derailed you couldn't have derailed they couldn't have derailed
V-ing perfect
I couldn't have been derailing you couldn't have been derailing she couldn't have been derailing we couldn't have been derailing you couldn't have been derailing they couldn't have been derailing
Interrogative form
Simple form
could I derail? could you derail? could she derail? could we derail? could you derail? could they derail?
V-ing form
could I be derailing? could you be derailing? could she be derailing? could we be derailing? could you be derailing? could they be derailing?
Perfect
could I have derailed? could you have derailed? could she have derailed? could we have derailed? could you have derailed? could they have derailed?
V-ing perfect
could I have been derailing? could you have been derailing? could she have been derailing? could we have been derailing? could you have been derailing? could they have been derailing?
Interro-negative form
Simple form
couldn't I derail? couldn't you derail? couldn't she derail? couldn't we derail? couldn't you derail? couldn't they derail?
V-ing form
couldn't I be derailing? couldn't you be derailing? couldn't she be derailing? couldn't we be derailing? couldn't you be derailing? couldn't they be derailing?
Perfect
couldn't I have derailed? couldn't you have derailed? couldn't she have derailed? couldn't we have derailed? couldn't you have derailed? couldn't they have derailed?
V-ing perfect
couldn't I have been derailing? couldn't you have been derailing? couldn't she have been derailing? couldn't we have been derailing? couldn't you have been derailing? couldn't they have been derailing?