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 couldn't observe
you couldn't observe
she couldn't observe
we couldn't observe
you couldn't observe
they couldn't observe 	I couldn't be observing
you couldn't be observing
she couldn't be observing
we couldn't be observing
you couldn't be observing
they couldn't be observing	I couldn't have observed
you couldn't have observed
she couldn't have observed
we couldn't have observed
you couldn't have observed
they couldn't have observed	I couldn't have been observing
you couldn't have been observing
she couldn't have been observing
we couldn't have been observing
you couldn't have been observing
they couldn't 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 	
couldn't I observe?
couldn't you observe?
couldn't she observe?
couldn't we observe?
couldn't you observe?
couldn't they observe? 	couldn't I be observing?
couldn't you be observing?
couldn't she be observing?
couldn't we be observing?
couldn't you be observing?
couldn't they be observing? 	couldn't I have observed?
couldn't you have observed?
couldn't she have observed?
couldn't we have observed?
couldn't you have observed?
couldn't they have observed? 	couldn't I have been observing?
couldn't you have been observing?
couldn't she have been observing?
couldn't we have been observing?
couldn't you have been observing?
couldn't they have been observing?