could sin
Regular verb: sin - sinned- sinned

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could sin
you could sin
she could sin
we could sin
you could sin
they could sin 	I could be sinning
you could be sinning
she could be sinning
we could be sinning
you could be sinning
they could be sinning	I could have sinned
you could have sinned
she could have sinned
we could have sinned
you could have sinned
they could have sinned	I could have been sinning
you could have been sinning
she could have been sinning
we could have been sinning
you could have been sinning
they could have been sinning	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not sin
you could not sin
she could not sin
we could not sin
you could not sin
they could not sin 	I could not be sinning
you could not be sinning
she could not be sinning
we could not be sinning
you could not be sinning
they could not be sinning	I could not have sinned
you could not have sinned
she could not have sinned
we could not have sinned
you could not have sinned
they could not have sinned	I could not have been sinning
you could not have been sinning
she could not have been sinning
we could not have been sinning
you could not have been sinning
they could not have been sinning	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I sin?
could you sin?
could she sin?
could we sin?
could you sin?
could they sin? 	could I be sinning?
could you be sinning?
could she be sinning?
could we be sinning?
could you be sinning?
could they be sinning? 	could I have sinned?
could you have sinned?
could she have sinned?
could we have sinned?
could you have sinned?
could they have sinned? 	could I have been sinning?
could you have been sinning?
could she have been sinning?
could we have been sinning?
could you have been sinning?
could they have been sinning? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not sin?
could you not sin?
could she not sin?
could we not sin?
could you not sin?
could they not sin? 	could I not be sinning?
could you not be sinning?
could she not be sinning?
could we not be sinning?
could you not be sinning?
could they not be sinning? 	could I not have sinned?
could you not have sinned?
could she not have sinned?
could we not have sinned?
could you not have sinned?
could they not have sinned? 	could I not have been sinning?
could you not have been sinning?
could she not have been sinning?
could we not have been sinning?
could you not have been sinning?
could they not have been sinning?