English verb conjugation
MUST UNDERSTAND

Irregular verb: understand - understood - understood

Affirmation

Simple form	V-ing form
I must understand you must understand he must understand we must understand you must understand they must understand	I must be understanding you must be understanding he must be understanding we must be understanding you must be understanding they must be understanding
Perfect	V-ing perfect
I must have understood you must have understood he must have understood we must have understood you must have understood they must have understood	I must have been understanding you must have been understanding he must have been understanding we must have been understanding you must have been understanding they must have been understanding

Negation

Simple form	V-ing form
I must not understand you must not understand he must not understand we must not understand you must not understand they must not understand	I must not be understanding you must not be understanding he must not be understanding we must not be understanding you must not be understanding they must not be understanding
Perfect	V-ing perfect
I must not have understood you must not have understood he must not have understood we must not have understood you must not have understood they must not have understood	I must not have been understanding you must not have been understanding he must not have been understanding we must not have been understanding you must not have been understanding they must not have been understanding

Interrogative form

Simple form	V-ing form
must I understand? must you understand? must he understand? must we understand? must you understand? must they understand?	must I be understanding? must you be understanding? must he be understanding? must we be understanding? must you be understanding? must they be understanding?
Perfect	V-ing perfect
must I have understood? must you have understood? must he have understood? must we have understood? must you have understood? must they have understood?	must I have been understanding? must you have been understanding? must he have been understanding? must we have been understanding? must you have been understanding? must they have been understanding?

Interro-negative form

Simple form	V-ing form
must I not understand? must you not understand? must he not understand? must we not understand? must you not understand? must they not understand?	must I not be understanding? must you not be understanding? must he not be understanding? must we not be understanding? must you not be understanding? must they not be understanding?
Perfect	V-ing perfect
must I not have understood? must you not have understood? must he not have understood? must we not have understood? must you not have understood? must they not have understood?	must I not have been understanding? must you not have been understanding? must he not have been understanding? must we not have been understanding? must you not have been understanding? must they not have been understanding?