could investigate
Verbo regular: investigate - investigated- investigated

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could investigate
you could investigate
she could investigate
we could investigate
you could investigate
they could investigate 	I could be investigating
you could be investigating
she could be investigating
we could be investigating
you could be investigating
they could be investigating	I could have investigated
you could have investigated
she could have investigated
we could have investigated
you could have investigated
they could have investigated	I could have been investigating
you could have been investigating
she could have been investigating
we could have been investigating
you could have been investigating
they could have been investigating	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I couldn't investigate
you couldn't investigate
she couldn't investigate
we couldn't investigate
you couldn't investigate
they couldn't investigate 	I couldn't be investigating
you couldn't be investigating
she couldn't be investigating
we couldn't be investigating
you couldn't be investigating
they couldn't be investigating	I couldn't have investigated
you couldn't have investigated
she couldn't have investigated
we couldn't have investigated
you couldn't have investigated
they couldn't have investigated	I couldn't have been investigating
you couldn't have been investigating
she couldn't have been investigating
we couldn't have been investigating
you couldn't have been investigating
they couldn't have been investigating	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I investigate?
could you investigate?
could she investigate?
could we investigate?
could you investigate?
could they investigate? 	could I be investigating?
could you be investigating?
could she be investigating?
could we be investigating?
could you be investigating?
could they be investigating? 	could I have investigated?
could you have investigated?
could she have investigated?
could we have investigated?
could you have investigated?
could they have investigated? 	could I have been investigating?
could you have been investigating?
could she have been investigating?
could we have been investigating?
could you have been investigating?
could they have been investigating? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
couldn't I investigate?
couldn't you investigate?
couldn't she investigate?
couldn't we investigate?
couldn't you investigate?
couldn't they investigate? 	couldn't I be investigating?
couldn't you be investigating?
couldn't she be investigating?
couldn't we be investigating?
couldn't you be investigating?
couldn't they be investigating? 	couldn't I have investigated?
couldn't you have investigated?
couldn't she have investigated?
couldn't we have investigated?
couldn't you have investigated?
couldn't they have investigated? 	couldn't I have been investigating?
couldn't you have been investigating?
couldn't she have been investigating?
couldn't we have been investigating?
couldn't you have been investigating?
couldn't they have been investigating?