must cough
Regular verb: cough - coughed- coughed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must cough
you must cough
he must cough
we must cough
you must cough
they must cough 	I must be coughing
you must be coughing
he must be coughing
we must be coughing
you must be coughing
they must be coughing	I must have coughed
you must have coughed
he must have coughed
we must have coughed
you must have coughed
they must have coughed	I must have been coughing
you must have been coughing
he must have been coughing
we must have been coughing
you must have been coughing
they must have been coughing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not cough
you must not cough
he must not cough
we must not cough
you must not cough
they must not cough 	I must not be coughing
you must not be coughing
he must not be coughing
we must not be coughing
you must not be coughing
they must not be coughing	I must not have coughed
you must not have coughed
he must not have coughed
we must not have coughed
you must not have coughed
they must not have coughed	I must not have been coughing
you must not have been coughing
he must not have been coughing
we must not have been coughing
you must not have been coughing
they must not have been coughing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I cough?
must you cough?
must he cough?
must we cough?
must you cough?
must they cough? 	must I be coughing?
must you be coughing?
must he be coughing?
must we be coughing?
must you be coughing?
must they be coughing? 	must I have coughed?
must you have coughed?
must he have coughed?
must we have coughed?
must you have coughed?
must they have coughed? 	must I have been coughing?
must you have been coughing?
must he have been coughing?
must we have been coughing?
must you have been coughing?
must they have been coughing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not cough?
must you not cough?
must he not cough?
must we not cough?
must you not cough?
must they not cough? 	must I not be coughing?
must you not be coughing?
must he not be coughing?
must we not be coughing?
must you not be coughing?
must they not be coughing? 	must I not have coughed?
must you not have coughed?
must he not have coughed?
must we not have coughed?
must you not have coughed?
must they not have coughed? 	must I not have been coughing?
must you not have been coughing?
must he not have been coughing?
must we not have been coughing?
must you not have been coughing?
must they not have been coughing?