could observe
Verbo regular: observe - observed- observed

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could observe
you could observe
he could observe
we could observe
you could observe
they could observe 	I could be observing
you could be observing
he could be observing
we could be observing
you could be observing
they could be observing	I could have observed
you could have observed
he 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
he could have been observing
we could have been observing
you could have been observing
they could have been observing	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could not observe
you could not observe
he 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
he 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
he 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
he 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 com V-ing 	Perfeito 	Perfeito com V-ing 	
could I observe?
could you observe?
could he observe?
could we observe?
could you observe?
could they observe? 	could I be observing?
could you be observing?
could he be observing?
could we be observing?
could you be observing?
could they be observing? 	could I have observed?
could you have observed?
could he 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 he have been observing?
could we have been observing?
could you have been observing?
could they have been observing? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I not observe?
could you not observe?
could he 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 he 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 he 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 he not have been observing?
could we not have been observing?
could you not have been observing?
could they not have been observing?