could observe
Verbo regular: observe - observed- observed

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could observe
you could observe
she could observe
we could observe
you could observe
they could observe 	I could be observing
you could be observing
she could be observing
we could be observing
you could be observing
they could be observing	I could have observed
you could have observed
she could have observed
we could have observed
you could have observed
they could have observed	I could have been observing
you could have been observing
she could have been observing
we could have been observing
you could have been observing
they could have been observing	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could not observe
you could not observe
she could not observe
we could not observe
you could not observe
they could not observe 	I could not be observing
you could not be observing
she could not be observing
we could not be observing
you could not be observing
they could not be observing	I could not have observed
you could not have observed
she could not have observed
we could not have observed
you could not have observed
they could not have observed	I could not have been observing
you could not have been observing
she could not have been observing
we could not have been observing
you could not have been observing
they could not have been observing	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I observe?
could you observe?
could she observe?
could we observe?
could you observe?
could they observe? 	could I be observing?
could you be observing?
could she be observing?
could we be observing?
could you be observing?
could they be observing? 	could I have observed?
could you have observed?
could she have observed?
could we have observed?
could you have observed?
could they have observed? 	could I have been observing?
could you have been observing?
could she have been observing?
could we have been observing?
could you have been observing?
could they have been observing? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I not observe?
could you not observe?
could she not observe?
could we not observe?
could you not observe?
could they not observe? 	could I not be observing?
could you not be observing?
could she not be observing?
could we not be observing?
could you not be observing?
could they not be observing? 	could I not have observed?
could you not have observed?
could she not have observed?
could we not have observed?
could you not have observed?
could they not have observed? 	could I not have been observing?
could you not have been observing?
could she not have been observing?
could we not have been observing?
could you not have been observing?
could they not have been observing?