English verb conjugation
COULD TREPAN

Regular verb: trepan - trepanned - trepanned

Affirmation

Simple form	V-ing form
I could trepan you could trepan he could trepan we could trepan you could trepan they could trepan	I could be trepanning you could be trepanning he could be trepanning we could be trepanning you could be trepanning they could be trepanning
Perfect	V-ing perfect
I could have trepanned you could have trepanned he could have trepanned we could have trepanned you could have trepanned they could have trepanned	I could have been trepanning you could have been trepanning he could have been trepanning we could have been trepanning you could have been trepanning they could have been trepanning

Negation

Simple form	V-ing form
I couldn't trepan you couldn't trepan he couldn't trepan we couldn't trepan you couldn't trepan they couldn't trepan	I couldn't be trepanning you couldn't be trepanning he couldn't be trepanning we couldn't be trepanning you couldn't be trepanning they couldn't be trepanning
Perfect	V-ing perfect
I couldn't have trepanned you couldn't have trepanned he couldn't have trepanned we couldn't have trepanned you couldn't have trepanned they couldn't have trepanned	I couldn't have been trepanning you couldn't have been trepanning he couldn't have been trepanning we couldn't have been trepanning you couldn't have been trepanning they couldn't have been trepanning

Interrogative form

Simple form	V-ing form
could I trepan? could you trepan? could he trepan? could we trepan? could you trepan? could they trepan?	could I be trepanning? could you be trepanning? could he be trepanning? could we be trepanning? could you be trepanning? could they be trepanning?
Perfect	V-ing perfect
could I have trepanned? could you have trepanned? could he have trepanned? could we have trepanned? could you have trepanned? could they have trepanned?	could I have been trepanning? could you have been trepanning? could he have been trepanning? could we have been trepanning? could you have been trepanning? could they have been trepanning?

Interro-negative form

Simple form	V-ing form
couldn't I trepan? couldn't you trepan? couldn't he trepan? couldn't we trepan? couldn't you trepan? couldn't they trepan?	couldn't I be trepanning? couldn't you be trepanning? couldn't he be trepanning? couldn't we be trepanning? couldn't you be trepanning? couldn't they be trepanning?
Perfect	V-ing perfect
couldn't I have trepanned? couldn't you have trepanned? couldn't he have trepanned? couldn't we have trepanned? couldn't you have trepanned? couldn't they have trepanned?	couldn't I have been trepanning? couldn't you have been trepanning? couldn't he have been trepanning? couldn't we have been trepanning? couldn't you have been trepanning? couldn't they have been trepanning?