|much, many, some||more||most|
|bad, badly, ill||worse||worst|
|far||farther, further||farthest, furthest*|
|old||older, elder||oldest, eldest|
*Note: The words further and furthest can be used to convey ideas of additional numbers (further experiments), greater quantity (further information) and greater distance (further to Perth). However, if you use farther and farthest you must refer to only physical distance.