I could submit you could submit he could submit we could submit you could submit they could submit
V-ing form
I could be submitting you could be submitting he could be submitting we could be submitting you could be submitting they could be submitting
Perfect
I could have submitted you could have submitted he could have submitted we could have submitted you could have submitted they could have submitted
V-ing perfect
I could have been submitting you could have been submitting he could have been submitting we could have been submitting you could have been submitting they could have been submitting
Negation
Simple form
I could not submit you could not submit he could not submit we could not submit you could not submit they could not submit
V-ing form
I could not be submitting you could not be submitting he could not be submitting we could not be submitting you could not be submitting they could not be submitting
Perfect
I could not have submitted you could not have submitted he could not have submitted we could not have submitted you could not have submitted they could not have submitted
V-ing perfect
I could not have been submitting you could not have been submitting he could not have been submitting we could not have been submitting you could not have been submitting they could not have been submitting
Interrogative form
Simple form
could I submit? could you submit? could he submit? could we submit? could you submit? could they submit?
V-ing form
could I be submitting? could you be submitting? could he be submitting? could we be submitting? could you be submitting? could they be submitting?
Perfect
could I have submitted? could you have submitted? could he have submitted? could we have submitted? could you have submitted? could they have submitted?
V-ing perfect
could I have been submitting? could you have been submitting? could he have been submitting? could we have been submitting? could you have been submitting? could they have been submitting?
Interro-negative form
Simple form
could I not submit? could you not submit? could he not submit? could we not submit? could you not submit? could they not submit?
V-ing form
could I not be submitting? could you not be submitting? could he not be submitting? could we not be submitting? could you not be submitting? could they not be submitting?
Perfect
could I not have submitted? could you not have submitted? could he not have submitted? could we not have submitted? could you not have submitted? could they not have submitted?
V-ing perfect
could I not have been submitting? could you not have been submitting? could he not have been submitting? could we not have been submitting? could you not have been submitting? could they not have been submitting?