can sum
Verbo regular: sum - summed- summed

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I can sum
you can sum
he can sum
we can sum
you can sum
they can sum 	I can be summing
you can be summing
he can be summing
we can be summing
you can be summing
they can be summing	I can have summed
you can have summed
he can have summed
we can have summed
you can have summed
they can have summed	I can have been summing
you can have been summing
he can have been summing
we can have been summing
you can have been summing
they can have been summing	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I cannot sum
you cannot sum
he cannot sum
we cannot sum
you cannot sum
they cannot sum 	I cannot be summing
you cannot be summing
he cannot be summing
we cannot be summing
you cannot be summing
they cannot be summing	I cannot have summed
you cannot have summed
he cannot have summed
we cannot have summed
you cannot have summed
they cannot have summed	I cannot have been summing
you cannot have been summing
he cannot have been summing
we cannot have been summing
you cannot have been summing
they cannot have been summing	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can I sum?
can you sum?
can he sum?
can we sum?
can you sum?
can they sum? 	can I be summing?
can you be summing?
can he be summing?
can we be summing?
can you be summing?
can they be summing? 	can I have summed?
can you have summed?
can he have summed?
can we have summed?
can you have summed?
can they have summed? 	can I have been summing?
can you have been summing?
can he have been summing?
can we have been summing?
can you have been summing?
can they have been summing? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can I not sum?
can you not sum?
can he not sum?
can we not sum?
can you not sum?
can they not sum? 	can I not be summing?
can you not be summing?
can he not be summing?
can we not be summing?
can you not be summing?
can they not be summing? 	can I not have summed?
can you not have summed?
can he not have summed?
can we not have summed?
can you not have summed?
can they not have summed? 	can I not have been summing?
can you not have been summing?
can he not have been summing?
can we not have been summing?
can you not have been summing?
can they not have been summing?