can weaken
Verbo regular: weaken - weakened- weakened

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I can weaken
you can weaken
he can weaken
we can weaken
you can weaken
they can weaken 	I can be weakening
you can be weakening
he can be weakening
we can be weakening
you can be weakening
they can be weakening	I can have weakened
you can have weakened
he can have weakened
we can have weakened
you can have weakened
they can have weakened	I can have been weakening
you can have been weakening
he can have been weakening
we can have been weakening
you can have been weakening
they can have been weakening	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I cannot weaken
you cannot weaken
he cannot weaken
we cannot weaken
you cannot weaken
they cannot weaken 	I cannot be weakening
you cannot be weakening
he cannot be weakening
we cannot be weakening
you cannot be weakening
they cannot be weakening	I cannot have weakened
you cannot have weakened
he cannot have weakened
we cannot have weakened
you cannot have weakened
they cannot have weakened	I cannot have been weakening
you cannot have been weakening
he cannot have been weakening
we cannot have been weakening
you cannot have been weakening
they cannot have been weakening	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can I weaken?
can you weaken?
can he weaken?
can we weaken?
can you weaken?
can they weaken? 	can I be weakening?
can you be weakening?
can he be weakening?
can we be weakening?
can you be weakening?
can they be weakening? 	can I have weakened?
can you have weakened?
can he have weakened?
can we have weakened?
can you have weakened?
can they have weakened? 	can I have been weakening?
can you have been weakening?
can he have been weakening?
can we have been weakening?
can you have been weakening?
can they have been weakening? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can I not weaken?
can you not weaken?
can he not weaken?
can we not weaken?
can you not weaken?
can they not weaken? 	can I not be weakening?
can you not be weakening?
can he not be weakening?
can we not be weakening?
can you not be weakening?
can they not be weakening? 	can I not have weakened?
can you not have weakened?
can he not have weakened?
can we not have weakened?
can you not have weakened?
can they not have weakened? 	can I not have been weakening?
can you not have been weakening?
can he not have been weakening?
can we not have been weakening?
can you not have been weakening?
can they not have been weakening?