can sign
Verbo regular: sign - signed- signed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can sign
you can sign
he can sign
we can sign
you can sign
they can sign 	I can be signing
you can be signing
he can be signing
we can be signing
you can be signing
they can be signing	I can have signed
you can have signed
he can have signed
we can have signed
you can have signed
they can have signed	I can have been signing
you can have been signing
he can have been signing
we can have been signing
you can have been signing
they can have been signing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I cannot sign
you cannot sign
he cannot sign
we cannot sign
you cannot sign
they cannot sign 	I cannot be signing
you cannot be signing
he cannot be signing
we cannot be signing
you cannot be signing
they cannot be signing	I cannot have signed
you cannot have signed
he cannot have signed
we cannot have signed
you cannot have signed
they cannot have signed	I cannot have been signing
you cannot have been signing
he cannot have been signing
we cannot have been signing
you cannot have been signing
they cannot have been signing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I sign?
can you sign?
can he sign?
can we sign?
can you sign?
can they sign? 	can I be signing?
can you be signing?
can he be signing?
can we be signing?
can you be signing?
can they be signing? 	can I have signed?
can you have signed?
can he have signed?
can we have signed?
can you have signed?
can they have signed? 	can I have been signing?
can you have been signing?
can he have been signing?
can we have been signing?
can you have been signing?
can they have been signing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I not sign?
can you not sign?
can he not sign?
can we not sign?
can you not sign?
can they not sign? 	can I not be signing?
can you not be signing?
can he not be signing?
can we not be signing?
can you not be signing?
can they not be signing? 	can I not have signed?
can you not have signed?
can he not have signed?
can we not have signed?
can you not have signed?
can they not have signed? 	can I not have been signing?
can you not have been signing?
can he not have been signing?
can we not have been signing?
can you not have been signing?
can they not have been signing?