could approximate
Regular verb: approximate - approximated- approximated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could approximate
you could approximate
he could approximate
we could approximate
you could approximate
they could approximate 	I could be approximating
you could be approximating
he could be approximating
we could be approximating
you could be approximating
they could be approximating	I could have approximated
you could have approximated
he could have approximated
we could have approximated
you could have approximated
they could have approximated	I could have been approximating
you could have been approximating
he could have been approximating
we could have been approximating
you could have been approximating
they could have been approximating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not approximate
you could not approximate
he could not approximate
we could not approximate
you could not approximate
they could not approximate 	I could not be approximating
you could not be approximating
he could not be approximating
we could not be approximating
you could not be approximating
they could not be approximating	I could not have approximated
you could not have approximated
he could not have approximated
we could not have approximated
you could not have approximated
they could not have approximated	I could not have been approximating
you could not have been approximating
he could not have been approximating
we could not have been approximating
you could not have been approximating
they could not have been approximating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I approximate?
could you approximate?
could he approximate?
could we approximate?
could you approximate?
could they approximate? 	could I be approximating?
could you be approximating?
could he be approximating?
could we be approximating?
could you be approximating?
could they be approximating? 	could I have approximated?
could you have approximated?
could he have approximated?
could we have approximated?
could you have approximated?
could they have approximated? 	could I have been approximating?
could you have been approximating?
could he have been approximating?
could we have been approximating?
could you have been approximating?
could they have been approximating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not approximate?
could you not approximate?
could he not approximate?
could we not approximate?
could you not approximate?
could they not approximate? 	could I not be approximating?
could you not be approximating?
could he not be approximating?
could we not be approximating?
could you not be approximating?
could they not be approximating? 	could I not have approximated?
could you not have approximated?
could he not have approximated?
could we not have approximated?
could you not have approximated?
could they not have approximated? 	could I not have been approximating?
could you not have been approximating?
could he not have been approximating?
could we not have been approximating?
could you not have been approximating?
could they not have been approximating?