could subtract
Verbo regular: subtract - subtracted- subtracted

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could subtract
you could subtract
she could subtract
we could subtract
you could subtract
they could subtract 	I could be subtracting
you could be subtracting
she could be subtracting
we could be subtracting
you could be subtracting
they could be subtracting	I could have subtracted
you could have subtracted
she could have subtracted
we could have subtracted
you could have subtracted
they could have subtracted	I could have been subtracting
you could have been subtracting
she could have been subtracting
we could have been subtracting
you could have been subtracting
they could have been subtracting	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could not subtract
you could not subtract
she could not subtract
we could not subtract
you could not subtract
they could not subtract 	I could not be subtracting
you could not be subtracting
she could not be subtracting
we could not be subtracting
you could not be subtracting
they could not be subtracting	I could not have subtracted
you could not have subtracted
she could not have subtracted
we could not have subtracted
you could not have subtracted
they could not have subtracted	I could not have been subtracting
you could not have been subtracting
she could not have been subtracting
we could not have been subtracting
you could not have been subtracting
they could not have been subtracting	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I subtract?
could you subtract?
could she subtract?
could we subtract?
could you subtract?
could they subtract? 	could I be subtracting?
could you be subtracting?
could she be subtracting?
could we be subtracting?
could you be subtracting?
could they be subtracting? 	could I have subtracted?
could you have subtracted?
could she have subtracted?
could we have subtracted?
could you have subtracted?
could they have subtracted? 	could I have been subtracting?
could you have been subtracting?
could she have been subtracting?
could we have been subtracting?
could you have been subtracting?
could they have been subtracting? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I not subtract?
could you not subtract?
could she not subtract?
could we not subtract?
could you not subtract?
could they not subtract? 	could I not be subtracting?
could you not be subtracting?
could she not be subtracting?
could we not be subtracting?
could you not be subtracting?
could they not be subtracting? 	could I not have subtracted?
could you not have subtracted?
could she not have subtracted?
could we not have subtracted?
could you not have subtracted?
could they not have subtracted? 	could I not have been subtracting?
could you not have been subtracting?
could she not have been subtracting?
could we not have been subtracting?
could you not have been subtracting?
could they not have been subtracting?