English verb conjugation
MUST CLACK

Regular verb: clack - clacked - clacked

Affirmation

Simple form	V-ing form
I must clack you must clack he must clack we must clack you must clack they must clack	I must be clacking you must be clacking he must be clacking we must be clacking you must be clacking they must be clacking
Perfect	V-ing perfect
I must have clacked you must have clacked he must have clacked we must have clacked you must have clacked they must have clacked	I must have been clacking you must have been clacking he must have been clacking we must have been clacking you must have been clacking they must have been clacking

Negation

Simple form	V-ing form
I mustn't clack you mustn't clack he mustn't clack we mustn't clack you mustn't clack they mustn't clack	I mustn't be clacking you mustn't be clacking he mustn't be clacking we mustn't be clacking you mustn't be clacking they mustn't be clacking
Perfect	V-ing perfect
I mustn't have clacked you mustn't have clacked he mustn't have clacked we mustn't have clacked you mustn't have clacked they mustn't have clacked	I mustn't have been clacking you mustn't have been clacking he mustn't have been clacking we mustn't have been clacking you mustn't have been clacking they mustn't have been clacking

Interrogative form

Simple form	V-ing form
must I clack? must you clack? must he clack? must we clack? must you clack? must they clack?	must I be clacking? must you be clacking? must he be clacking? must we be clacking? must you be clacking? must they be clacking?
Perfect	V-ing perfect
must I have clacked? must you have clacked? must he have clacked? must we have clacked? must you have clacked? must they have clacked?	must I have been clacking? must you have been clacking? must he have been clacking? must we have been clacking? must you have been clacking? must they have been clacking?

Interro-negative form

Simple form	V-ing form
mustn't I clack? mustn't you clack? mustn't he clack? mustn't we clack? mustn't you clack? mustn't they clack?	mustn't I be clacking? mustn't you be clacking? mustn't he be clacking? mustn't we be clacking? mustn't you be clacking? mustn't they be clacking?
Perfect	V-ing perfect
mustn't I have clacked? mustn't you have clacked? mustn't he have clacked? mustn't we have clacked? mustn't you have clacked? mustn't they have clacked?	mustn't I have been clacking? mustn't you have been clacking? mustn't he have been clacking? mustn't we have been clacking? mustn't you have been clacking? mustn't they have been clacking?