I could suggest you could suggest he could suggest we could suggest you could suggest they could suggest
V-ing form
I could be suggesting you could be suggesting he could be suggesting we could be suggesting you could be suggesting they could be suggesting
Perfect
I could have suggested you could have suggested he could have suggested we could have suggested you could have suggested they could have suggested
V-ing perfect
I could have been suggesting you could have been suggesting he could have been suggesting we could have been suggesting you could have been suggesting they could have been suggesting
Negation
Simple form
I could not suggest you could not suggest he could not suggest we could not suggest you could not suggest they could not suggest
V-ing form
I could not be suggesting you could not be suggesting he could not be suggesting we could not be suggesting you could not be suggesting they could not be suggesting
Perfect
I could not have suggested you could not have suggested he could not have suggested we could not have suggested you could not have suggested they could not have suggested
V-ing perfect
I could not have been suggesting you could not have been suggesting he could not have been suggesting we could not have been suggesting you could not have been suggesting they could not have been suggesting
Interrogative form
Simple form
could I suggest? could you suggest? could he suggest? could we suggest? could you suggest? could they suggest?
V-ing form
could I be suggesting? could you be suggesting? could he be suggesting? could we be suggesting? could you be suggesting? could they be suggesting?
Perfect
could I have suggested? could you have suggested? could he have suggested? could we have suggested? could you have suggested? could they have suggested?
V-ing perfect
could I have been suggesting? could you have been suggesting? could he have been suggesting? could we have been suggesting? could you have been suggesting? could they have been suggesting?
Interro-negative form
Simple form
could I not suggest? could you not suggest? could he not suggest? could we not suggest? could you not suggest? could they not suggest?
V-ing form
could I not be suggesting? could you not be suggesting? could he not be suggesting? could we not be suggesting? could you not be suggesting? could they not be suggesting?
Perfect
could I not have suggested? could you not have suggested? could he not have suggested? could we not have suggested? could you not have suggested? could they not have suggested?
V-ing perfect
could I not have been suggesting? could you not have been suggesting? could he not have been suggesting? could we not have been suggesting? could you not have been suggesting? could they not have been suggesting?