could estimate
Regular verb: estimate - estimated- estimated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could estimate
you could estimate
he could estimate
we could estimate
you could estimate
they could estimate 	I could be estimating
you could be estimating
he could be estimating
we could be estimating
you could be estimating
they could be estimating	I could have estimated
you could have estimated
he could have estimated
we could have estimated
you could have estimated
they could have estimated	I could have been estimating
you could have been estimating
he could have been estimating
we could have been estimating
you could have been estimating
they could have been estimating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not estimate
you could not estimate
he could not estimate
we could not estimate
you could not estimate
they could not estimate 	I could not be estimating
you could not be estimating
he could not be estimating
we could not be estimating
you could not be estimating
they could not be estimating	I could not have estimated
you could not have estimated
he could not have estimated
we could not have estimated
you could not have estimated
they could not have estimated	I could not have been estimating
you could not have been estimating
he could not have been estimating
we could not have been estimating
you could not have been estimating
they could not have been estimating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I estimate?
could you estimate?
could he estimate?
could we estimate?
could you estimate?
could they estimate? 	could I be estimating?
could you be estimating?
could he be estimating?
could we be estimating?
could you be estimating?
could they be estimating? 	could I have estimated?
could you have estimated?
could he have estimated?
could we have estimated?
could you have estimated?
could they have estimated? 	could I have been estimating?
could you have been estimating?
could he have been estimating?
could we have been estimating?
could you have been estimating?
could they have been estimating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not estimate?
could you not estimate?
could he not estimate?
could we not estimate?
could you not estimate?
could they not estimate? 	could I not be estimating?
could you not be estimating?
could he not be estimating?
could we not be estimating?
could you not be estimating?
could they not be estimating? 	could I not have estimated?
could you not have estimated?
could he not have estimated?
could we not have estimated?
could you not have estimated?
could they not have estimated? 	could I not have been estimating?
could you not have been estimating?
could he not have been estimating?
could we not have been estimating?
could you not have been estimating?
could they not have been estimating?