I could plod you could plod he could plod we could plod you could plod they could plod
V-ing form
I could be plodding you could be plodding he could be plodding we could be plodding you could be plodding they could be plodding
Perfect
I could have plodded you could have plodded he could have plodded we could have plodded you could have plodded they could have plodded
V-ing perfect
I could have been plodding you could have been plodding he could have been plodding we could have been plodding you could have been plodding they could have been plodding
Negation
Simple form
I could not plod you could not plod he could not plod we could not plod you could not plod they could not plod
V-ing form
I could not be plodding you could not be plodding he could not be plodding we could not be plodding you could not be plodding they could not be plodding
Perfect
I could not have plodded you could not have plodded he could not have plodded we could not have plodded you could not have plodded they could not have plodded
V-ing perfect
I could not have been plodding you could not have been plodding he could not have been plodding we could not have been plodding you could not have been plodding they could not have been plodding
Interrogative form
Simple form
could I plod? could you plod? could he plod? could we plod? could you plod? could they plod?
V-ing form
could I be plodding? could you be plodding? could he be plodding? could we be plodding? could you be plodding? could they be plodding?
Perfect
could I have plodded? could you have plodded? could he have plodded? could we have plodded? could you have plodded? could they have plodded?
V-ing perfect
could I have been plodding? could you have been plodding? could he have been plodding? could we have been plodding? could you have been plodding? could they have been plodding?
Interro-negative form
Simple form
could I not plod? could you not plod? could he not plod? could we not plod? could you not plod? could they not plod?
V-ing form
could I not be plodding? could you not be plodding? could he not be plodding? could we not be plodding? could you not be plodding? could they not be plodding?
Perfect
could I not have plodded? could you not have plodded? could he not have plodded? could we not have plodded? could you not have plodded? could they not have plodded?
V-ing perfect
could I not have been plodding? could you not have been plodding? could he not have been plodding? could we not have been plodding? could you not have been plodding? could they not have been plodding?