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 couldn't underpin you couldn't underpin he couldn't underpin we couldn't underpin you couldn't underpin they couldn't underpin	I couldn't be underpinning you couldn't be underpinning he couldn't be underpinning we couldn't be underpinning you couldn't be underpinning they couldn't be underpinning
Perfect	V-ing perfect
I couldn't have underpinned you couldn't have underpinned he couldn't have underpinned we couldn't have underpinned you couldn't have underpinned they couldn't have underpinned	I couldn't have been underpinning you couldn't have been underpinning he couldn't have been underpinning we couldn't have been underpinning you couldn't have been underpinning they couldn't 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
couldn't I underpin? couldn't you underpin? couldn't he underpin? couldn't we underpin? couldn't you underpin? couldn't they underpin?	couldn't I be underpinning? couldn't you be underpinning? couldn't he be underpinning? couldn't we be underpinning? couldn't you be underpinning? couldn't they be underpinning?
Perfect	V-ing perfect
couldn't I have underpinned? couldn't you have underpinned? couldn't he have underpinned? couldn't we have underpinned? couldn't you have underpinned? couldn't they have underpinned?	couldn't I have been underpinning? couldn't you have been underpinning? couldn't he have been underpinning? couldn't we have been underpinning? couldn't you have been underpinning? couldn't they have been underpinning?