I could navigate you could navigate he could navigate we could navigate you could navigate they could navigate
V-ing form
I could be navigating you could be navigating he could be navigating we could be navigating you could be navigating they could be navigating
Perfect
I could have navigated you could have navigated he could have navigated we could have navigated you could have navigated they could have navigated
V-ing perfect
I could have been navigating you could have been navigating he could have been navigating we could have been navigating you could have been navigating they could have been navigating
Negation
Simple form
I could not navigate you could not navigate he could not navigate we could not navigate you could not navigate they could not navigate
V-ing form
I could not be navigating you could not be navigating he could not be navigating we could not be navigating you could not be navigating they could not be navigating
Perfect
I could not have navigated you could not have navigated he could not have navigated we could not have navigated you could not have navigated they could not have navigated
V-ing perfect
I could not have been navigating you could not have been navigating he could not have been navigating we could not have been navigating you could not have been navigating they could not have been navigating
Interrogative form
Simple form
could I navigate? could you navigate? could he navigate? could we navigate? could you navigate? could they navigate?
V-ing form
could I be navigating? could you be navigating? could he be navigating? could we be navigating? could you be navigating? could they be navigating?
Perfect
could I have navigated? could you have navigated? could he have navigated? could we have navigated? could you have navigated? could they have navigated?
V-ing perfect
could I have been navigating? could you have been navigating? could he have been navigating? could we have been navigating? could you have been navigating? could they have been navigating?
Interro-negative form
Simple form
could I not navigate? could you not navigate? could he not navigate? could we not navigate? could you not navigate? could they not navigate?
V-ing form
could I not be navigating? could you not be navigating? could he not be navigating? could we not be navigating? could you not be navigating? could they not be navigating?
Perfect
could I not have navigated? could you not have navigated? could he not have navigated? could we not have navigated? could you not have navigated? could they not have navigated?
V-ing perfect
could I not have been navigating? could you not have been navigating? could he not have been navigating? could we not have been navigating? could you not have been navigating? could they not have been navigating?