English verb conjugation
COULD UNDERPIN

Regular verb: underpin - underpinned - underpinned

Affirmation

Simple form	V-ing form
I could underpin you could underpin he could underpin we could underpin you could underpin they could underpin	I could be underpinning you could be underpinning he could be underpinning we could be underpinning you could be underpinning they could be underpinning
Perfect	V-ing perfect
I could have underpinned you could have underpinned he could have underpinned we could have underpinned you could have underpinned they could have underpinned	I could have been underpinning you could have been underpinning he could have been underpinning we could have been underpinning you could have been underpinning they could have been underpinning

Negation

Simple form	V-ing form
I could not underpin you could not underpin he could not underpin we could not underpin you could not underpin they could not underpin	I could not be underpinning you could not be underpinning he could not be underpinning we could not be underpinning you could not be underpinning they could not be underpinning
Perfect	V-ing perfect
I could not have underpinned you could not have underpinned he could not have underpinned we could not have underpinned you could not have underpinned they could not have underpinned	I could not have been underpinning you could not have been underpinning he could not have been underpinning we could not have been underpinning you could not have been underpinning they could not have been underpinning

Interrogative form

Simple form	V-ing form
could I underpin? could you underpin? could he underpin? could we underpin? could you underpin? could they underpin?	could I be underpinning? could you be underpinning? could he be underpinning? could we be underpinning? could you be underpinning? could they be underpinning?
Perfect	V-ing perfect
could I have underpinned? could you have underpinned? could he have underpinned? could we have underpinned? could you have underpinned? could they have underpinned?	could I have been underpinning? could you have been underpinning? could he have been underpinning? could we have been underpinning? could you have been underpinning? could they have been underpinning?

Interro-negative form

Simple form	V-ing form
could I not underpin? could you not underpin? could he not underpin? could we not underpin? could you not underpin? could they not underpin?	could I not be underpinning? could you not be underpinning? could he not be underpinning? could we not be underpinning? could you not be underpinning? could they not be underpinning?
Perfect	V-ing perfect
could I not have underpinned? could you not have underpinned? could he not have underpinned? could we not have underpinned? could you not have underpinned? could they not have underpinned?	could I not have been underpinning? could you not have been underpinning? could he not have been underpinning? could we not have been underpinning? could you not have been underpinning? could they not have been underpinning?