English verb conjugation
MUST RETAIN

Regular verb: retain - retained - retained

Affirmation

Simple form	V-ing form
I must retain you must retain she must retain we must retain you must retain they must retain	I must be retaining you must be retaining she must be retaining we must be retaining you must be retaining they must be retaining
Perfect	V-ing perfect
I must have retained you must have retained she must have retained we must have retained you must have retained they must have retained	I must have been retaining you must have been retaining she must have been retaining we must have been retaining you must have been retaining they must have been retaining

Negation

Simple form	V-ing form
I mustn't retain you mustn't retain she mustn't retain we mustn't retain you mustn't retain they mustn't retain	I mustn't be retaining you mustn't be retaining she mustn't be retaining we mustn't be retaining you mustn't be retaining they mustn't be retaining
Perfect	V-ing perfect
I mustn't have retained you mustn't have retained she mustn't have retained we mustn't have retained you mustn't have retained they mustn't have retained	I mustn't have been retaining you mustn't have been retaining she mustn't have been retaining we mustn't have been retaining you mustn't have been retaining they mustn't have been retaining

Interrogative form

Simple form	V-ing form
must I retain? must you retain? must she retain? must we retain? must you retain? must they retain?	must I be retaining? must you be retaining? must she be retaining? must we be retaining? must you be retaining? must they be retaining?
Perfect	V-ing perfect
must I have retained? must you have retained? must she have retained? must we have retained? must you have retained? must they have retained?	must I have been retaining? must you have been retaining? must she have been retaining? must we have been retaining? must you have been retaining? must they have been retaining?

Interro-negative form

Simple form	V-ing form
mustn't I retain? mustn't you retain? mustn't she retain? mustn't we retain? mustn't you retain? mustn't they retain?	mustn't I be retaining? mustn't you be retaining? mustn't she be retaining? mustn't we be retaining? mustn't you be retaining? mustn't they be retaining?
Perfect	V-ing perfect
mustn't I have retained? mustn't you have retained? mustn't she have retained? mustn't we have retained? mustn't you have retained? mustn't they have retained?	mustn't I have been retaining? mustn't you have been retaining? mustn't she have been retaining? mustn't we have been retaining? mustn't you have been retaining? mustn't they have been retaining?