could obsess
Regular verb: obsess - obsessed- obsessed

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

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

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

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