English verb conjugation
MUST BACKFIT

Irregular verb: backfit - backfit, backfitted - backfit, backfitted

Affirmation

Simple form	V-ing form
I must backfit you must backfit he must backfit we must backfit you must backfit they must backfit	I must be backfiting you must be backfiting he must be backfiting we must be backfiting you must be backfiting they must be backfiting
Perfect	V-ing perfect
I must have backfit, backfitted you must have backfit, backfitted he must have backfit, backfitted we must have backfit, backfitted you must have backfit, backfitted they must have backfit, backfitted	I must have been backfiting you must have been backfiting he must have been backfiting we must have been backfiting you must have been backfiting they must have been backfiting

Negation

Simple form	V-ing form
I must not backfit you must not backfit he must not backfit we must not backfit you must not backfit they must not backfit	I must not be backfiting you must not be backfiting he must not be backfiting we must not be backfiting you must not be backfiting they must not be backfiting
Perfect	V-ing perfect
I must not have backfit, backfitted you must not have backfit, backfitted he must not have backfit, backfitted we must not have backfit, backfitted you must not have backfit, backfitted they must not have backfit, backfitted	I must not have been backfiting you must not have been backfiting he must not have been backfiting we must not have been backfiting you must not have been backfiting they must not have been backfiting

Interrogative form

Simple form	V-ing form
must I backfit? must you backfit? must he backfit? must we backfit? must you backfit? must they backfit?	must I be backfiting? must you be backfiting? must he be backfiting? must we be backfiting? must you be backfiting? must they be backfiting?
Perfect	V-ing perfect
must I have backfit, backfitted? must you have backfit, backfitted? must he have backfit, backfitted? must we have backfit, backfitted? must you have backfit, backfitted? must they have backfit, backfitted?	must I have been backfiting? must you have been backfiting? must he have been backfiting? must we have been backfiting? must you have been backfiting? must they have been backfiting?

Interro-negative form

Simple form	V-ing form
must I not backfit? must you not backfit? must he not backfit? must we not backfit? must you not backfit? must they not backfit?	must I not be backfiting? must you not be backfiting? must he not be backfiting? must we not be backfiting? must you not be backfiting? must they not be backfiting?
Perfect	V-ing perfect
must I not have backfit, backfitted? must you not have backfit, backfitted? must he not have backfit, backfitted? must we not have backfit, backfitted? must you not have backfit, backfitted? must they not have backfit, backfitted?	must I not have been backfiting? must you not have been backfiting? must he not have been backfiting? must we not have been backfiting? must you not have been backfiting? must they not have been backfiting?