English verb conjugation
COULD UNDERESTIMATE

Regular verb: underestimate - underestimated - underestimated

Affirmation

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

Negation

Simple form	V-ing form
I could not underestimate you could not underestimate he could not underestimate we could not underestimate you could not underestimate they could not underestimate	I could not be underestimating you could not be underestimating he could not be underestimating we could not be underestimating you could not be underestimating they could not be underestimating
Perfect	V-ing perfect
I could not have underestimated you could not have underestimated he could not have underestimated we could not have underestimated you could not have underestimated they could not have underestimated	I could not have been underestimating you could not have been underestimating he could not have been underestimating we could not have been underestimating you could not have been underestimating they could not have been underestimating

Interrogative form

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

Interro-negative form

Simple form	V-ing form
could I not underestimate? could you not underestimate? could he not underestimate? could we not underestimate? could you not underestimate? could they not underestimate?	could I not be underestimating? could you not be underestimating? could he not be underestimating? could we not be underestimating? could you not be underestimating? could they not be underestimating?
Perfect	V-ing perfect
could I not have underestimated? could you not have underestimated? could he not have underestimated? could we not have underestimated? could you not have underestimated? could they not have underestimated?	could I not have been underestimating? could you not have been underestimating? could he not have been underestimating? could we not have been underestimating? could you not have been underestimating? could they not have been underestimating?