can frown
Regular verb: frown - frowned- frowned

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

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

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

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