English verb conjugation
MUST CLACK

Regular verb: clack - clacked - clacked

Affirmation

Simple form	V-ing form
I must clack you must clack she must clack we must clack you must clack they must clack	I must be clacking you must be clacking she 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 she 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 she 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 must not clack you must not clack she must not clack we must not clack you must not clack they must not clack	I must not be clacking you must not be clacking she must not be clacking we must not be clacking you must not be clacking they must not be clacking
Perfect	V-ing perfect
I must not have clacked you must not have clacked she must not have clacked we must not have clacked you must not have clacked they must not have clacked	I must not have been clacking you must not have been clacking she must not have been clacking we must not have been clacking you must not have been clacking they must not have been clacking

Interrogative form

Simple form	V-ing form
must I clack? must you clack? must she clack? must we clack? must you clack? must they clack?	must I be clacking? must you be clacking? must she 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 she 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 she 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
must I not clack? must you not clack? must she not clack? must we not clack? must you not clack? must they not clack?	must I not be clacking? must you not be clacking? must she not be clacking? must we not be clacking? must you not be clacking? must they not be clacking?
Perfect	V-ing perfect
must I not have clacked? must you not have clacked? must she not have clacked? must we not have clacked? must you not have clacked? must they not have clacked?	must I not have been clacking? must you not have been clacking? must she not have been clacking? must we not have been clacking? must you not have been clacking? must they not have been clacking?