English verb conjugation
MUST WEAKEN

Regular verb: weaken - weakened - weakened

Affirmation

Simple form	V-ing form
I must weaken you must weaken he must weaken we must weaken you must weaken they must weaken	I must be weakening you must be weakening he must be weakening we must be weakening you must be weakening they must be weakening
Perfect	V-ing perfect
I must have weakened you must have weakened he must have weakened we must have weakened you must have weakened they must have weakened	I must have been weakening you must have been weakening he must have been weakening we must have been weakening you must have been weakening they must have been weakening

Negation

Simple form	V-ing form
I must not weaken you must not weaken he must not weaken we must not weaken you must not weaken they must not weaken	I must not be weakening you must not be weakening he must not be weakening we must not be weakening you must not be weakening they must not be weakening
Perfect	V-ing perfect
I must not have weakened you must not have weakened he must not have weakened we must not have weakened you must not have weakened they must not have weakened	I must not have been weakening you must not have been weakening he must not have been weakening we must not have been weakening you must not have been weakening they must not have been weakening

Interrogative form

Simple form	V-ing form
must I weaken? must you weaken? must he weaken? must we weaken? must you weaken? must they weaken?	must I be weakening? must you be weakening? must he be weakening? must we be weakening? must you be weakening? must they be weakening?
Perfect	V-ing perfect
must I have weakened? must you have weakened? must he have weakened? must we have weakened? must you have weakened? must they have weakened?	must I have been weakening? must you have been weakening? must he have been weakening? must we have been weakening? must you have been weakening? must they have been weakening?

Interro-negative form

Simple form	V-ing form
must I not weaken? must you not weaken? must he not weaken? must we not weaken? must you not weaken? must they not weaken?	must I not be weakening? must you not be weakening? must he not be weakening? must we not be weakening? must you not be weakening? must they not be weakening?
Perfect	V-ing perfect
must I not have weakened? must you not have weakened? must he not have weakened? must we not have weakened? must you not have weakened? must they not have weakened?	must I not have been weakening? must you not have been weakening? must he not have been weakening? must we not have been weakening? must you not have been weakening? must they not have been weakening?