could sibilate
Regular verb: sibilate - sibilated- sibilated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could sibilate
you could sibilate
he could sibilate
we could sibilate
you could sibilate
they could sibilate 	I could be sibilating
you could be sibilating
he could be sibilating
we could be sibilating
you could be sibilating
they could be sibilating	I could have sibilated
you could have sibilated
he could have sibilated
we could have sibilated
you could have sibilated
they could have sibilated	I could have been sibilating
you could have been sibilating
he could have been sibilating
we could have been sibilating
you could have been sibilating
they could have been sibilating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not sibilate
you could not sibilate
he could not sibilate
we could not sibilate
you could not sibilate
they could not sibilate 	I could not be sibilating
you could not be sibilating
he could not be sibilating
we could not be sibilating
you could not be sibilating
they could not be sibilating	I could not have sibilated
you could not have sibilated
he could not have sibilated
we could not have sibilated
you could not have sibilated
they could not have sibilated	I could not have been sibilating
you could not have been sibilating
he could not have been sibilating
we could not have been sibilating
you could not have been sibilating
they could not have been sibilating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I sibilate?
could you sibilate?
could he sibilate?
could we sibilate?
could you sibilate?
could they sibilate? 	could I be sibilating?
could you be sibilating?
could he be sibilating?
could we be sibilating?
could you be sibilating?
could they be sibilating? 	could I have sibilated?
could you have sibilated?
could he have sibilated?
could we have sibilated?
could you have sibilated?
could they have sibilated? 	could I have been sibilating?
could you have been sibilating?
could he have been sibilating?
could we have been sibilating?
could you have been sibilating?
could they have been sibilating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not sibilate?
could you not sibilate?
could he not sibilate?
could we not sibilate?
could you not sibilate?
could they not sibilate? 	could I not be sibilating?
could you not be sibilating?
could he not be sibilating?
could we not be sibilating?
could you not be sibilating?
could they not be sibilating? 	could I not have sibilated?
could you not have sibilated?
could he not have sibilated?
could we not have sibilated?
could you not have sibilated?
could they not have sibilated? 	could I not have been sibilating?
could you not have been sibilating?
could he not have been sibilating?
could we not have been sibilating?
could you not have been sibilating?
could they not have been sibilating?