I could centrifuge you could centrifuge she could centrifuge we could centrifuge you could centrifuge they could centrifuge
V-ing form
I could be centrifuging you could be centrifuging she could be centrifuging we could be centrifuging you could be centrifuging they could be centrifuging
Perfect
I could have centrifuged you could have centrifuged she could have centrifuged we could have centrifuged you could have centrifuged they could have centrifuged
V-ing perfect
I could have been centrifuging you could have been centrifuging she could have been centrifuging we could have been centrifuging you could have been centrifuging they could have been centrifuging
Negation
Simple form
I could not centrifuge you could not centrifuge she could not centrifuge we could not centrifuge you could not centrifuge they could not centrifuge
V-ing form
I could not be centrifuging you could not be centrifuging she could not be centrifuging we could not be centrifuging you could not be centrifuging they could not be centrifuging
Perfect
I could not have centrifuged you could not have centrifuged she could not have centrifuged we could not have centrifuged you could not have centrifuged they could not have centrifuged
V-ing perfect
I could not have been centrifuging you could not have been centrifuging she could not have been centrifuging we could not have been centrifuging you could not have been centrifuging they could not have been centrifuging
Interrogative form
Simple form
could I centrifuge? could you centrifuge? could she centrifuge? could we centrifuge? could you centrifuge? could they centrifuge?
V-ing form
could I be centrifuging? could you be centrifuging? could she be centrifuging? could we be centrifuging? could you be centrifuging? could they be centrifuging?
Perfect
could I have centrifuged? could you have centrifuged? could she have centrifuged? could we have centrifuged? could you have centrifuged? could they have centrifuged?
V-ing perfect
could I have been centrifuging? could you have been centrifuging? could she have been centrifuging? could we have been centrifuging? could you have been centrifuging? could they have been centrifuging?
Interro-negative form
Simple form
could I not centrifuge? could you not centrifuge? could she not centrifuge? could we not centrifuge? could you not centrifuge? could they not centrifuge?
V-ing form
could I not be centrifuging? could you not be centrifuging? could she not be centrifuging? could we not be centrifuging? could you not be centrifuging? could they not be centrifuging?
Perfect
could I not have centrifuged? could you not have centrifuged? could she not have centrifuged? could we not have centrifuged? could you not have centrifuged? could they not have centrifuged?
V-ing perfect
could I not have been centrifuging? could you not have been centrifuging? could she not have been centrifuging? could we not have been centrifuging? could you not have been centrifuging? could they not have been centrifuging?