could single
Regular verb: single - singled- singled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could single
you could single
he could single
we could single
you could single
they could single 	I could be singling
you could be singling
he could be singling
we could be singling
you could be singling
they could be singling	I could have singled
you could have singled
he could have singled
we could have singled
you could have singled
they could have singled	I could have been singling
you could have been singling
he could have been singling
we could have been singling
you could have been singling
they could have been singling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't single
you couldn't single
he couldn't single
we couldn't single
you couldn't single
they couldn't single 	I couldn't be singling
you couldn't be singling
he couldn't be singling
we couldn't be singling
you couldn't be singling
they couldn't be singling	I couldn't have singled
you couldn't have singled
he couldn't have singled
we couldn't have singled
you couldn't have singled
they couldn't have singled	I couldn't have been singling
you couldn't have been singling
he couldn't have been singling
we couldn't have been singling
you couldn't have been singling
they couldn't have been singling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I single?
could you single?
could he single?
could we single?
could you single?
could they single? 	could I be singling?
could you be singling?
could he be singling?
could we be singling?
could you be singling?
could they be singling? 	could I have singled?
could you have singled?
could he have singled?
could we have singled?
could you have singled?
could they have singled? 	could I have been singling?
could you have been singling?
could he have been singling?
could we have been singling?
could you have been singling?
could they have been singling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I single?
couldn't you single?
couldn't he single?
couldn't we single?
couldn't you single?
couldn't they single? 	couldn't I be singling?
couldn't you be singling?
couldn't he be singling?
couldn't we be singling?
couldn't you be singling?
couldn't they be singling? 	couldn't I have singled?
couldn't you have singled?
couldn't he have singled?
couldn't we have singled?
couldn't you have singled?
couldn't they have singled? 	couldn't I have been singling?
couldn't you have been singling?
couldn't he have been singling?
couldn't we have been singling?
couldn't you have been singling?
couldn't they have been singling?