could frown
Regular verb: frown - frowned- frowned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could frown
you could frown
she could frown
we could frown
you could frown
they could frown 	I could be frowning
you could be frowning
she could be frowning
we could be frowning
you could be frowning
they could be frowning	I could have frowned
you could have frowned
she could have frowned
we could have frowned
you could have frowned
they could have frowned	I could have been frowning
you could have been frowning
she could have been frowning
we could have been frowning
you could have been frowning
they could have been frowning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't frown
you couldn't frown
she couldn't frown
we couldn't frown
you couldn't frown
they couldn't frown 	I couldn't be frowning
you couldn't be frowning
she couldn't be frowning
we couldn't be frowning
you couldn't be frowning
they couldn't be frowning	I couldn't have frowned
you couldn't have frowned
she couldn't have frowned
we couldn't have frowned
you couldn't have frowned
they couldn't have frowned	I couldn't have been frowning
you couldn't have been frowning
she couldn't have been frowning
we couldn't have been frowning
you couldn't have been frowning
they couldn't have been frowning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I frown?
could you frown?
could she frown?
could we frown?
could you frown?
could they frown? 	could I be frowning?
could you be frowning?
could she be frowning?
could we be frowning?
could you be frowning?
could they be frowning? 	could I have frowned?
could you have frowned?
could she have frowned?
could we have frowned?
could you have frowned?
could they have frowned? 	could I have been frowning?
could you have been frowning?
could she have been frowning?
could we have been frowning?
could you have been frowning?
could they have been frowning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I frown?
couldn't you frown?
couldn't she frown?
couldn't we frown?
couldn't you frown?
couldn't they frown? 	couldn't I be frowning?
couldn't you be frowning?
couldn't she be frowning?
couldn't we be frowning?
couldn't you be frowning?
couldn't they be frowning? 	couldn't I have frowned?
couldn't you have frowned?
couldn't she have frowned?
couldn't we have frowned?
couldn't you have frowned?
couldn't they have frowned? 	couldn't I have been frowning?
couldn't you have been frowning?
couldn't she have been frowning?
couldn't we have been frowning?
couldn't you have been frowning?
couldn't they have been frowning?