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 mustn't understand you mustn't understand he mustn't understand we mustn't understand you mustn't understand they mustn't understand	I mustn't be understanding you mustn't be understanding he mustn't be understanding we mustn't be understanding you mustn't be understanding they mustn't be understanding
Perfect	V-ing perfect
I mustn't have understood you mustn't have understood he mustn't have understood we mustn't have understood you mustn't have understood they mustn't have understood	I mustn't have been understanding you mustn't have been understanding he mustn't have been understanding we mustn't have been understanding you mustn't have been understanding they mustn't 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
mustn't I understand? mustn't you understand? mustn't he understand? mustn't we understand? mustn't you understand? mustn't they understand?	mustn't I be understanding? mustn't you be understanding? mustn't he be understanding? mustn't we be understanding? mustn't you be understanding? mustn't they be understanding?
Perfect	V-ing perfect
mustn't I have understood? mustn't you have understood? mustn't he have understood? mustn't we have understood? mustn't you have understood? mustn't they have understood?	mustn't I have been understanding? mustn't you have been understanding? mustn't he have been understanding? mustn't we have been understanding? mustn't you have been understanding? mustn't they have been understanding?