could rust
Verbo regular: rust - rusted- rusted

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could rust
you could rust
he could rust
we could rust
you could rust
they could rust 	I could be rusting
you could be rusting
he could be rusting
we could be rusting
you could be rusting
they could be rusting	I could have rusted
you could have rusted
he could have rusted
we could have rusted
you could have rusted
they could have rusted	I could have been rusting
you could have been rusting
he could have been rusting
we could have been rusting
you could have been rusting
they could have been rusting	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I couldn't rust
you couldn't rust
he couldn't rust
we couldn't rust
you couldn't rust
they couldn't rust 	I couldn't be rusting
you couldn't be rusting
he couldn't be rusting
we couldn't be rusting
you couldn't be rusting
they couldn't be rusting	I couldn't have rusted
you couldn't have rusted
he couldn't have rusted
we couldn't have rusted
you couldn't have rusted
they couldn't have rusted	I couldn't have been rusting
you couldn't have been rusting
he couldn't have been rusting
we couldn't have been rusting
you couldn't have been rusting
they couldn't have been rusting	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I rust?
could you rust?
could he rust?
could we rust?
could you rust?
could they rust? 	could I be rusting?
could you be rusting?
could he be rusting?
could we be rusting?
could you be rusting?
could they be rusting? 	could I have rusted?
could you have rusted?
could he have rusted?
could we have rusted?
could you have rusted?
could they have rusted? 	could I have been rusting?
could you have been rusting?
could he have been rusting?
could we have been rusting?
could you have been rusting?
could they have been rusting? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
couldn't I rust?
couldn't you rust?
couldn't he rust?
couldn't we rust?
couldn't you rust?
couldn't they rust? 	couldn't I be rusting?
couldn't you be rusting?
couldn't he be rusting?
couldn't we be rusting?
couldn't you be rusting?
couldn't they be rusting? 	couldn't I have rusted?
couldn't you have rusted?
couldn't he have rusted?
couldn't we have rusted?
couldn't you have rusted?
couldn't they have rusted? 	couldn't I have been rusting?
couldn't you have been rusting?
couldn't he have been rusting?
couldn't we have been rusting?
couldn't you have been rusting?
couldn't they have been rusting?