a blacksmith's Device with a short head much like a chilly chisel set transversely on to a cope with and utilised, when struck by using a hammer, for removing lengths of iron barsis the set whose things are those elements that belong to all sets in ? S displaystyle mathcal S D?ch trong m?i ?ng d?ng B?t k? b?n ?ang dùng ?ng d?ng nào, ch? c?n sao c