I could starboard you could starboard he could starboard we could starboard you could starboard they could starboard
V-ing form
I could be starboarding you could be starboarding he could be starboarding we could be starboarding you could be starboarding they could be starboarding
Perfect
I could have starboarded you could have starboarded he could have starboarded we could have starboarded you could have starboarded they could have starboarded
V-ing perfect
I could have been starboarding you could have been starboarding he could have been starboarding we could have been starboarding you could have been starboarding they could have been starboarding
Negation
Simple form
I could not starboard you could not starboard he could not starboard we could not starboard you could not starboard they could not starboard
V-ing form
I could not be starboarding you could not be starboarding he could not be starboarding we could not be starboarding you could not be starboarding they could not be starboarding
Perfect
I could not have starboarded you could not have starboarded he could not have starboarded we could not have starboarded you could not have starboarded they could not have starboarded
V-ing perfect
I could not have been starboarding you could not have been starboarding he could not have been starboarding we could not have been starboarding you could not have been starboarding they could not have been starboarding
Interrogative form
Simple form
could I starboard? could you starboard? could he starboard? could we starboard? could you starboard? could they starboard?
V-ing form
could I be starboarding? could you be starboarding? could he be starboarding? could we be starboarding? could you be starboarding? could they be starboarding?
Perfect
could I have starboarded? could you have starboarded? could he have starboarded? could we have starboarded? could you have starboarded? could they have starboarded?
V-ing perfect
could I have been starboarding? could you have been starboarding? could he have been starboarding? could we have been starboarding? could you have been starboarding? could they have been starboarding?
Interro-negative form
Simple form
could I not starboard? could you not starboard? could he not starboard? could we not starboard? could you not starboard? could they not starboard?
V-ing form
could I not be starboarding? could you not be starboarding? could he not be starboarding? could we not be starboarding? could you not be starboarding? could they not be starboarding?
Perfect
could I not have starboarded? could you not have starboarded? could he not have starboarded? could we not have starboarded? could you not have starboarded? could they not have starboarded?
V-ing perfect
could I not have been starboarding? could you not have been starboarding? could he not have been starboarding? could we not have been starboarding? could you not have been starboarding? could they not have been starboarding?