English verb conjugation
SHOULD UNDERPIN

Regular verb: underpin - underpinned - underpinned

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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