could obsess
Regular verb: obsess - obsessed- obsessed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could obsess
you could obsess
she could obsess
we could obsess
you could obsess
they could obsess 	I could be obsessing
you could be obsessing
she could be obsessing
we could be obsessing
you could be obsessing
they could be obsessing	I could have obsessed
you could have obsessed
she 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
she 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
she 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
she 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
she 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
she 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 she obsess?
could we obsess?
could you obsess?
could they obsess? 	could I be obsessing?
could you be obsessing?
could she be obsessing?
could we be obsessing?
could you be obsessing?
could they be obsessing? 	could I have obsessed?
could you have obsessed?
could she 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 she 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 she 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 she 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 she 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 she have been obsessing?
couldn't we have been obsessing?
couldn't you have been obsessing?
couldn't they have been obsessing?