could shrill
Regular verb: shrill - shrilled- shrilled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could shrill
you could shrill
she could shrill
we could shrill
you could shrill
they could shrill 	I could be shrilling
you could be shrilling
she could be shrilling
we could be shrilling
you could be shrilling
they could be shrilling	I could have shrilled
you could have shrilled
she could have shrilled
we could have shrilled
you could have shrilled
they could have shrilled	I could have been shrilling
you could have been shrilling
she could have been shrilling
we could have been shrilling
you could have been shrilling
they could have been shrilling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't shrill
you couldn't shrill
she couldn't shrill
we couldn't shrill
you couldn't shrill
they couldn't shrill 	I couldn't be shrilling
you couldn't be shrilling
she couldn't be shrilling
we couldn't be shrilling
you couldn't be shrilling
they couldn't be shrilling	I couldn't have shrilled
you couldn't have shrilled
she couldn't have shrilled
we couldn't have shrilled
you couldn't have shrilled
they couldn't have shrilled	I couldn't have been shrilling
you couldn't have been shrilling
she couldn't have been shrilling
we couldn't have been shrilling
you couldn't have been shrilling
they couldn't have been shrilling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I shrill?
could you shrill?
could she shrill?
could we shrill?
could you shrill?
could they shrill? 	could I be shrilling?
could you be shrilling?
could she be shrilling?
could we be shrilling?
could you be shrilling?
could they be shrilling? 	could I have shrilled?
could you have shrilled?
could she have shrilled?
could we have shrilled?
could you have shrilled?
could they have shrilled? 	could I have been shrilling?
could you have been shrilling?
could she have been shrilling?
could we have been shrilling?
could you have been shrilling?
could they have been shrilling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I shrill?
couldn't you shrill?
couldn't she shrill?
couldn't we shrill?
couldn't you shrill?
couldn't they shrill? 	couldn't I be shrilling?
couldn't you be shrilling?
couldn't she be shrilling?
couldn't we be shrilling?
couldn't you be shrilling?
couldn't they be shrilling? 	couldn't I have shrilled?
couldn't you have shrilled?
couldn't she have shrilled?
couldn't we have shrilled?
couldn't you have shrilled?
couldn't they have shrilled? 	couldn't I have been shrilling?
couldn't you have been shrilling?
couldn't she have been shrilling?
couldn't we have been shrilling?
couldn't you have been shrilling?
couldn't they have been shrilling?