English verb conjugation
COULD TRAIL

Regular verb: trail - trailed - trailed

Affirmation

Simple form	V-ing form
I could trail you could trail he could trail we could trail you could trail they could trail	I could be trailing you could be trailing he could be trailing we could be trailing you could be trailing they could be trailing
Perfect	V-ing perfect
I could have trailed you could have trailed he could have trailed we could have trailed you could have trailed they could have trailed	I could have been trailing you could have been trailing he could have been trailing we could have been trailing you could have been trailing they could have been trailing

Negation

Simple form	V-ing form
I couldn't trail you couldn't trail he couldn't trail we couldn't trail you couldn't trail they couldn't trail	I couldn't be trailing you couldn't be trailing he couldn't be trailing we couldn't be trailing you couldn't be trailing they couldn't be trailing
Perfect	V-ing perfect
I couldn't have trailed you couldn't have trailed he couldn't have trailed we couldn't have trailed you couldn't have trailed they couldn't have trailed	I couldn't have been trailing you couldn't have been trailing he couldn't have been trailing we couldn't have been trailing you couldn't have been trailing they couldn't have been trailing

Interrogative form

Simple form	V-ing form
could I trail? could you trail? could he trail? could we trail? could you trail? could they trail?	could I be trailing? could you be trailing? could he be trailing? could we be trailing? could you be trailing? could they be trailing?
Perfect	V-ing perfect
could I have trailed? could you have trailed? could he have trailed? could we have trailed? could you have trailed? could they have trailed?	could I have been trailing? could you have been trailing? could he have been trailing? could we have been trailing? could you have been trailing? could they have been trailing?

Interro-negative form

Simple form	V-ing form
couldn't I trail? couldn't you trail? couldn't he trail? couldn't we trail? couldn't you trail? couldn't they trail?	couldn't I be trailing? couldn't you be trailing? couldn't he be trailing? couldn't we be trailing? couldn't you be trailing? couldn't they be trailing?
Perfect	V-ing perfect
couldn't I have trailed? couldn't you have trailed? couldn't he have trailed? couldn't we have trailed? couldn't you have trailed? couldn't they have trailed?	couldn't I have been trailing? couldn't you have been trailing? couldn't he have been trailing? couldn't we have been trailing? couldn't you have been trailing? couldn't they have been trailing?