can ascertain
Verbo regular: ascertain - ascertained- ascertained

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I can ascertain
you can ascertain
he can ascertain
we can ascertain
you can ascertain
they can ascertain 	I can be ascertaining
you can be ascertaining
he can be ascertaining
we can be ascertaining
you can be ascertaining
they can be ascertaining	I can have ascertained
you can have ascertained
he can have ascertained
we can have ascertained
you can have ascertained
they can have ascertained	I can have been ascertaining
you can have been ascertaining
he can have been ascertaining
we can have been ascertaining
you can have been ascertaining
they can have been ascertaining	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I cannot ascertain
you cannot ascertain
he cannot ascertain
we cannot ascertain
you cannot ascertain
they cannot ascertain 	I cannot be ascertaining
you cannot be ascertaining
he cannot be ascertaining
we cannot be ascertaining
you cannot be ascertaining
they cannot be ascertaining	I cannot have ascertained
you cannot have ascertained
he cannot have ascertained
we cannot have ascertained
you cannot have ascertained
they cannot have ascertained	I cannot have been ascertaining
you cannot have been ascertaining
he cannot have been ascertaining
we cannot have been ascertaining
you cannot have been ascertaining
they cannot have been ascertaining	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I ascertain?
can you ascertain?
can he ascertain?
can we ascertain?
can you ascertain?
can they ascertain? 	can I be ascertaining?
can you be ascertaining?
can he be ascertaining?
can we be ascertaining?
can you be ascertaining?
can they be ascertaining? 	can I have ascertained?
can you have ascertained?
can he have ascertained?
can we have ascertained?
can you have ascertained?
can they have ascertained? 	can I have been ascertaining?
can you have been ascertaining?
can he have been ascertaining?
can we have been ascertaining?
can you have been ascertaining?
can they have been ascertaining? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
can I not ascertain?
can you not ascertain?
can he not ascertain?
can we not ascertain?
can you not ascertain?
can they not ascertain? 	can I not be ascertaining?
can you not be ascertaining?
can he not be ascertaining?
can we not be ascertaining?
can you not be ascertaining?
can they not be ascertaining? 	can I not have ascertained?
can you not have ascertained?
can he not have ascertained?
can we not have ascertained?
can you not have ascertained?
can they not have ascertained? 	can I not have been ascertaining?
can you not have been ascertaining?
can he not have been ascertaining?
can we not have been ascertaining?
can you not have been ascertaining?
can they not have been ascertaining?