Образуйте множественное число существительных, оканчивающихся на –F/-FE. Shelf, calf, grief, cliff, life, knife, proof, reef, sheaf, wife, safe, gulf, self, elf, leaf, loaf, wolf, chief.

Shelf - shelves, calf - calves, grief - griefs, cliff - cliffs, life - lives, knife - knives, proof - proofs, reef - reefs, sheaf - sheaves, wife - wives, safe - safes, gulf - gulfs, self - selves, elf - elves, leaf - leaves, wolf - wolves, chief - chiefs.