could centrifuge
Regular verb: centrifuge - centrifuged- centrifuged

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could centrifuge
you could centrifuge
he could centrifuge
we could centrifuge
you could centrifuge
they could centrifuge 	I could be centrifuging
you could be centrifuging
he could be centrifuging
we could be centrifuging
you could be centrifuging
they could be centrifuging	I could have centrifuged
you could have centrifuged
he could have centrifuged
we could have centrifuged
you could have centrifuged
they could have centrifuged	I could have been centrifuging
you could have been centrifuging
he could have been centrifuging
we could have been centrifuging
you could have been centrifuging
they could have been centrifuging	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't centrifuge
you couldn't centrifuge
he couldn't centrifuge
we couldn't centrifuge
you couldn't centrifuge
they couldn't centrifuge 	I couldn't be centrifuging
you couldn't be centrifuging
he couldn't be centrifuging
we couldn't be centrifuging
you couldn't be centrifuging
they couldn't be centrifuging	I couldn't have centrifuged
you couldn't have centrifuged
he couldn't have centrifuged
we couldn't have centrifuged
you couldn't have centrifuged
they couldn't have centrifuged	I couldn't have been centrifuging
you couldn't have been centrifuging
he couldn't have been centrifuging
we couldn't have been centrifuging
you couldn't have been centrifuging
they couldn't have been centrifuging	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I centrifuge?
could you centrifuge?
could he centrifuge?
could we centrifuge?
could you centrifuge?
could they centrifuge? 	could I be centrifuging?
could you be centrifuging?
could he be centrifuging?
could we be centrifuging?
could you be centrifuging?
could they be centrifuging? 	could I have centrifuged?
could you have centrifuged?
could he have centrifuged?
could we have centrifuged?
could you have centrifuged?
could they have centrifuged? 	could I have been centrifuging?
could you have been centrifuging?
could he have been centrifuging?
could we have been centrifuging?
could you have been centrifuging?
could they have been centrifuging? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I centrifuge?
couldn't you centrifuge?
couldn't he centrifuge?
couldn't we centrifuge?
couldn't you centrifuge?
couldn't they centrifuge? 	couldn't I be centrifuging?
couldn't you be centrifuging?
couldn't he be centrifuging?
couldn't we be centrifuging?
couldn't you be centrifuging?
couldn't they be centrifuging? 	couldn't I have centrifuged?
couldn't you have centrifuged?
couldn't he have centrifuged?
couldn't we have centrifuged?
couldn't you have centrifuged?
couldn't they have centrifuged? 	couldn't I have been centrifuging?
couldn't you have been centrifuging?
couldn't he have been centrifuging?
couldn't we have been centrifuging?
couldn't you have been centrifuging?
couldn't they have been centrifuging?