could prototype
Regular verb: prototype - prototyped- prototyped

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could prototype
you could prototype
he could prototype
we could prototype
you could prototype
they could prototype 	I could be prototyping
you could be prototyping
he could be prototyping
we could be prototyping
you could be prototyping
they could be prototyping	I could have prototyped
you could have prototyped
he could have prototyped
we could have prototyped
you could have prototyped
they could have prototyped	I could have been prototyping
you could have been prototyping
he could have been prototyping
we could have been prototyping
you could have been prototyping
they could have been prototyping	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't prototype
you couldn't prototype
he couldn't prototype
we couldn't prototype
you couldn't prototype
they couldn't prototype 	I couldn't be prototyping
you couldn't be prototyping
he couldn't be prototyping
we couldn't be prototyping
you couldn't be prototyping
they couldn't be prototyping	I couldn't have prototyped
you couldn't have prototyped
he couldn't have prototyped
we couldn't have prototyped
you couldn't have prototyped
they couldn't have prototyped	I couldn't have been prototyping
you couldn't have been prototyping
he couldn't have been prototyping
we couldn't have been prototyping
you couldn't have been prototyping
they couldn't have been prototyping	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I prototype?
could you prototype?
could he prototype?
could we prototype?
could you prototype?
could they prototype? 	could I be prototyping?
could you be prototyping?
could he be prototyping?
could we be prototyping?
could you be prototyping?
could they be prototyping? 	could I have prototyped?
could you have prototyped?
could he have prototyped?
could we have prototyped?
could you have prototyped?
could they have prototyped? 	could I have been prototyping?
could you have been prototyping?
could he have been prototyping?
could we have been prototyping?
could you have been prototyping?
could they have been prototyping? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I prototype?
couldn't you prototype?
couldn't he prototype?
couldn't we prototype?
couldn't you prototype?
couldn't they prototype? 	couldn't I be prototyping?
couldn't you be prototyping?
couldn't he be prototyping?
couldn't we be prototyping?
couldn't you be prototyping?
couldn't they be prototyping? 	couldn't I have prototyped?
couldn't you have prototyped?
couldn't he have prototyped?
couldn't we have prototyped?
couldn't you have prototyped?
couldn't they have prototyped? 	couldn't I have been prototyping?
couldn't you have been prototyping?
couldn't he have been prototyping?
couldn't we have been prototyping?
couldn't you have been prototyping?
couldn't they have been prototyping?