must obsess
Regular verb: obsess - obsessed- obsessed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must obsess
you must obsess
she must obsess
we must obsess
you must obsess
they must obsess 	I must be obsessing
you must be obsessing
she must be obsessing
we must be obsessing
you must be obsessing
they must be obsessing	I must have obsessed
you must have obsessed
she must have obsessed
we must have obsessed
you must have obsessed
they must have obsessed	I must have been obsessing
you must have been obsessing
she must have been obsessing
we must have been obsessing
you must have been obsessing
they must have been obsessing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I mustn't obsess
you mustn't obsess
she mustn't obsess
we mustn't obsess
you mustn't obsess
they mustn't obsess 	I mustn't be obsessing
you mustn't be obsessing
she mustn't be obsessing
we mustn't be obsessing
you mustn't be obsessing
they mustn't be obsessing	I mustn't have obsessed
you mustn't have obsessed
she mustn't have obsessed
we mustn't have obsessed
you mustn't have obsessed
they mustn't have obsessed	I mustn't have been obsessing
you mustn't have been obsessing
she mustn't have been obsessing
we mustn't have been obsessing
you mustn't have been obsessing
they mustn't have been obsessing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I obsess?
must you obsess?
must she obsess?
must we obsess?
must you obsess?
must they obsess? 	must I be obsessing?
must you be obsessing?
must she be obsessing?
must we be obsessing?
must you be obsessing?
must they be obsessing? 	must I have obsessed?
must you have obsessed?
must she have obsessed?
must we have obsessed?
must you have obsessed?
must they have obsessed? 	must I have been obsessing?
must you have been obsessing?
must she have been obsessing?
must we have been obsessing?
must you have been obsessing?
must they have been obsessing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
mustn't I obsess?
mustn't you obsess?
mustn't she obsess?
mustn't we obsess?
mustn't you obsess?
mustn't they obsess? 	mustn't I be obsessing?
mustn't you be obsessing?
mustn't she be obsessing?
mustn't we be obsessing?
mustn't you be obsessing?
mustn't they be obsessing? 	mustn't I have obsessed?
mustn't you have obsessed?
mustn't she have obsessed?
mustn't we have obsessed?
mustn't you have obsessed?
mustn't they have obsessed? 	mustn't I have been obsessing?
mustn't you have been obsessing?
mustn't she have been obsessing?
mustn't we have been obsessing?
mustn't you have been obsessing?
mustn't they have been obsessing?