English verb conjugation
MUST CRACK

Regular verb: crack - cracked - cracked

Affirmation

Simple form	V-ing form
I must crack you must crack he must crack we must crack you must crack they must crack	I must be cracking you must be cracking he must be cracking we must be cracking you must be cracking they must be cracking
Perfect	V-ing perfect
I must have cracked you must have cracked he must have cracked we must have cracked you must have cracked they must have cracked	I must have been cracking you must have been cracking he must have been cracking we must have been cracking you must have been cracking they must have been cracking

Negation

Simple form	V-ing form
I mustn't crack you mustn't crack he mustn't crack we mustn't crack you mustn't crack they mustn't crack	I mustn't be cracking you mustn't be cracking he mustn't be cracking we mustn't be cracking you mustn't be cracking they mustn't be cracking
Perfect	V-ing perfect
I mustn't have cracked you mustn't have cracked he mustn't have cracked we mustn't have cracked you mustn't have cracked they mustn't have cracked	I mustn't have been cracking you mustn't have been cracking he mustn't have been cracking we mustn't have been cracking you mustn't have been cracking they mustn't have been cracking

Interrogative form

Simple form	V-ing form
must I crack? must you crack? must he crack? must we crack? must you crack? must they crack?	must I be cracking? must you be cracking? must he be cracking? must we be cracking? must you be cracking? must they be cracking?
Perfect	V-ing perfect
must I have cracked? must you have cracked? must he have cracked? must we have cracked? must you have cracked? must they have cracked?	must I have been cracking? must you have been cracking? must he have been cracking? must we have been cracking? must you have been cracking? must they have been cracking?

Interro-negative form

Simple form	V-ing form
mustn't I crack? mustn't you crack? mustn't he crack? mustn't we crack? mustn't you crack? mustn't they crack?	mustn't I be cracking? mustn't you be cracking? mustn't he be cracking? mustn't we be cracking? mustn't you be cracking? mustn't they be cracking?
Perfect	V-ing perfect
mustn't I have cracked? mustn't you have cracked? mustn't he have cracked? mustn't we have cracked? mustn't you have cracked? mustn't they have cracked?	mustn't I have been cracking? mustn't you have been cracking? mustn't he have been cracking? mustn't we have been cracking? mustn't you have been cracking? mustn't they have been cracking?