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
he could subtract
we could subtract
you could subtract
they could subtract 	I could be subtracting
you could be subtracting
he could be subtracting
we could be subtracting
you could be subtracting
they could be subtracting	I could have subtracted
you could have subtracted
he 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
he 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 couldn't subtract
you couldn't subtract
he couldn't subtract
we couldn't subtract
you couldn't subtract
they couldn't subtract 	I couldn't be subtracting
you couldn't be subtracting
he couldn't be subtracting
we couldn't be subtracting
you couldn't be subtracting
they couldn't be subtracting	I couldn't have subtracted
you couldn't have subtracted
he couldn't have subtracted
we couldn't have subtracted
you couldn't have subtracted
they couldn't have subtracted	I couldn't have been subtracting
you couldn't have been subtracting
he couldn't have been subtracting
we couldn't have been subtracting
you couldn't have been subtracting
they couldn't have been subtracting	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I subtract?
could you subtract?
could he subtract?
could we subtract?
could you subtract?
could they subtract? 	could I be subtracting?
could you be subtracting?
could he be subtracting?
could we be subtracting?
could you be subtracting?
could they be subtracting? 	could I have subtracted?
could you have subtracted?
could he 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 he 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 	
couldn't I subtract?
couldn't you subtract?
couldn't he subtract?
couldn't we subtract?
couldn't you subtract?
couldn't they subtract? 	couldn't I be subtracting?
couldn't you be subtracting?
couldn't he be subtracting?
couldn't we be subtracting?
couldn't you be subtracting?
couldn't they be subtracting? 	couldn't I have subtracted?
couldn't you have subtracted?
couldn't he have subtracted?
couldn't we have subtracted?
couldn't you have subtracted?
couldn't they have subtracted? 	couldn't I have been subtracting?
couldn't you have been subtracting?
couldn't he have been subtracting?
couldn't we have been subtracting?
couldn't you have been subtracting?
couldn't they have been subtracting?