could roil
Regular verb: roil - roiled- roiled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could roil
you could roil
he could roil
we could roil
you could roil
they could roil 	I could be roiling
you could be roiling
he could be roiling
we could be roiling
you could be roiling
they could be roiling	I could have roiled
you could have roiled
he could have roiled
we could have roiled
you could have roiled
they could have roiled	I could have been roiling
you could have been roiling
he could have been roiling
we could have been roiling
you could have been roiling
they could have been roiling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't roil
you couldn't roil
he couldn't roil
we couldn't roil
you couldn't roil
they couldn't roil 	I couldn't be roiling
you couldn't be roiling
he couldn't be roiling
we couldn't be roiling
you couldn't be roiling
they couldn't be roiling	I couldn't have roiled
you couldn't have roiled
he couldn't have roiled
we couldn't have roiled
you couldn't have roiled
they couldn't have roiled	I couldn't have been roiling
you couldn't have been roiling
he couldn't have been roiling
we couldn't have been roiling
you couldn't have been roiling
they couldn't have been roiling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I roil?
could you roil?
could he roil?
could we roil?
could you roil?
could they roil? 	could I be roiling?
could you be roiling?
could he be roiling?
could we be roiling?
could you be roiling?
could they be roiling? 	could I have roiled?
could you have roiled?
could he have roiled?
could we have roiled?
could you have roiled?
could they have roiled? 	could I have been roiling?
could you have been roiling?
could he have been roiling?
could we have been roiling?
could you have been roiling?
could they have been roiling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I roil?
couldn't you roil?
couldn't he roil?
couldn't we roil?
couldn't you roil?
couldn't they roil? 	couldn't I be roiling?
couldn't you be roiling?
couldn't he be roiling?
couldn't we be roiling?
couldn't you be roiling?
couldn't they be roiling? 	couldn't I have roiled?
couldn't you have roiled?
couldn't he have roiled?
couldn't we have roiled?
couldn't you have roiled?
couldn't they have roiled? 	couldn't I have been roiling?
couldn't you have been roiling?
couldn't he have been roiling?
couldn't we have been roiling?
couldn't you have been roiling?
couldn't they have been roiling?