I must underestimate you must underestimate she must underestimate we must underestimate you must underestimate they must underestimate
V-ing form
I must be underestimating you must be underestimating she must be underestimating we must be underestimating you must be underestimating they must be underestimating
Perfect
I must have underestimated you must have underestimated she must have underestimated we must have underestimated you must have underestimated they must have underestimated
V-ing perfect
I must have been underestimating you must have been underestimating she must have been underestimating we must have been underestimating you must have been underestimating they must have been underestimating
Negation
Simple form
I must not underestimate you must not underestimate she must not underestimate we must not underestimate you must not underestimate they must not underestimate
V-ing form
I must not be underestimating you must not be underestimating she must not be underestimating we must not be underestimating you must not be underestimating they must not be underestimating
Perfect
I must not have underestimated you must not have underestimated she must not have underestimated we must not have underestimated you must not have underestimated they must not have underestimated
V-ing perfect
I must not have been underestimating you must not have been underestimating she must not have been underestimating we must not have been underestimating you must not have been underestimating they must not have been underestimating
Interrogative form
Simple form
must I underestimate? must you underestimate? must she underestimate? must we underestimate? must you underestimate? must they underestimate?
V-ing form
must I be underestimating? must you be underestimating? must she be underestimating? must we be underestimating? must you be underestimating? must they be underestimating?
Perfect
must I have underestimated? must you have underestimated? must she have underestimated? must we have underestimated? must you have underestimated? must they have underestimated?
V-ing perfect
must I have been underestimating? must you have been underestimating? must she have been underestimating? must we have been underestimating? must you have been underestimating? must they have been underestimating?
Interro-negative form
Simple form
must I not underestimate? must you not underestimate? must she not underestimate? must we not underestimate? must you not underestimate? must they not underestimate?
V-ing form
must I not be underestimating? must you not be underestimating? must she not be underestimating? must we not be underestimating? must you not be underestimating? must they not be underestimating?
Perfect
must I not have underestimated? must you not have underestimated? must she not have underestimated? must we not have underestimated? must you not have underestimated? must they not have underestimated?
V-ing perfect
must I not have been underestimating? must you not have been underestimating? must she not have been underestimating? must we not have been underestimating? must you not have been underestimating? must they not have been underestimating?