could sing
Verbo irregular: sing - sang- sung

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could sing
you could sing
she could sing
we could sing
you could sing
they could sing 	I could be singing
you could be singing
she could be singing
we could be singing
you could be singing
they could be singing	I could have sung
you could have sung
she could have sung
we could have sung
you could have sung
they could have sung	I could have been singing
you could have been singing
she could have been singing
we could have been singing
you could have been singing
they could have been singing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't sing
you couldn't sing
she couldn't sing
we couldn't sing
you couldn't sing
they couldn't sing 	I couldn't be singing
you couldn't be singing
she couldn't be singing
we couldn't be singing
you couldn't be singing
they couldn't be singing	I couldn't have sung
you couldn't have sung
she couldn't have sung
we couldn't have sung
you couldn't have sung
they couldn't have sung	I couldn't have been singing
you couldn't have been singing
she couldn't have been singing
we couldn't have been singing
you couldn't have been singing
they couldn't have been singing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I sing?
could you sing?
could she sing?
could we sing?
could you sing?
could they sing? 	could I be singing?
could you be singing?
could she be singing?
could we be singing?
could you be singing?
could they be singing? 	could I have sung?
could you have sung?
could she have sung?
could we have sung?
could you have sung?
could they have sung? 	could I have been singing?
could you have been singing?
could she have been singing?
could we have been singing?
could you have been singing?
could they have been singing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I sing?
couldn't you sing?
couldn't she sing?
couldn't we sing?
couldn't you sing?
couldn't they sing? 	couldn't I be singing?
couldn't you be singing?
couldn't she be singing?
couldn't we be singing?
couldn't you be singing?
couldn't they be singing? 	couldn't I have sung?
couldn't you have sung?
couldn't she have sung?
couldn't we have sung?
couldn't you have sung?
couldn't they have sung? 	couldn't I have been singing?
couldn't you have been singing?
couldn't she have been singing?
couldn't we have been singing?
couldn't you have been singing?
couldn't they have been singing?