Is there any rule telling us how to change words ending with -f(e) into -fs or -ves?
For example, sometimes we can only add "s" to the following words ending with -f or -fe:beliefs, briefs, coifs, carafes, giraffes, safes, roofs.
However, sometimes we have to change the following words ending with -f or -fe into -ves: knife > knives, shelf > shelves, leaf > leaves, wolf > wolves, behalf > behalves, calf > calves, loaf > loaves, thief > thieves, wife > wives.
Other than rote-learning, are there any other ways to help memorise all these tricky words?
I'm sorry to be the bearer of bad news.