English verb conjugation
SHOULD UNDERESTIMATE

Regular verb: underestimate - underestimated - underestimated

Affirmation

Simple form	V-ing form
I'd underestimate you'd underestimate he'd underestimate we'd underestimate you'd underestimate they'd underestimate	I'd be underestimating you'd be underestimating he'd be underestimating we'd be underestimating you'd be underestimating they'd be underestimating
Perfect	V-ing perfect
I should've underestimated you should've underestimated he should've underestimated we should've underestimated you should've underestimated they should've underestimated	I should've been underestimating you should've been underestimating he should've been underestimating we should've been underestimating you should've been underestimating they should've been underestimating

Negation

Simple form	V-ing form
I shouldn't underestimate you shouldn't underestimate he shouldn't underestimate we shouldn't underestimate you shouldn't underestimate they shouldn't underestimate	I shouldn't be underestimating you shouldn't be underestimating he shouldn't be underestimating we shouldn't be underestimating you shouldn't be underestimating they shouldn't be underestimating
Perfect	V-ing perfect
I shouldn't have underestimated you shouldn't have underestimated he shouldn't have underestimated we shouldn't have underestimated you shouldn't have underestimated they shouldn't have underestimated	I shouldn't have been underestimating you shouldn't have been underestimating he shouldn't have been underestimating we shouldn't have been underestimating you shouldn't have been underestimating they shouldn't have been underestimating

Interrogative form

Simple form	V-ing form
should I underestimate? should you underestimate? should he underestimate? should we underestimate? should you underestimate? should they underestimate?	should I be underestimating? should you be underestimating? should he be underestimating? should we be underestimating? should you be underestimating? should they be underestimating?
Perfect	V-ing perfect
should I have underestimated? should you have underestimated? should he have underestimated? should we have underestimated? should you have underestimated? should they have underestimated?	should I have been underestimating? should you have been underestimating? should he have been underestimating? should we have been underestimating? should you have been underestimating? should they have been underestimating?

Interro-negative form

Simple form	V-ing form
shouldn't I underestimate? shouldn't you underestimate? shouldn't he underestimate? shouldn't we underestimate? shouldn't you underestimate? shouldn't they underestimate?	shouldn't I be underestimating? shouldn't you be underestimating? shouldn't he be underestimating? shouldn't we be underestimating? shouldn't you be underestimating? shouldn't they be underestimating?
Perfect	V-ing perfect
shouldn't I have underestimated? shouldn't you have underestimated? shouldn't he have underestimated? shouldn't we have underestimated? shouldn't you have underestimated? shouldn't they have underestimated?	shouldn't I have been underestimating? shouldn't you have been underestimating? shouldn't he have been underestimating? shouldn't we have been underestimating? shouldn't you have been underestimating? shouldn't they have been underestimating?