1517915 Tom is an unknown artist. Spamster 1 757941 The cause of the fire was unknown. NekoKanjya 1 263708 The cause of the accident is unknown. CK 1 324813 The whereabouts of the suspect is still unknown. CM 1 1636645 Her name was unknown. GeeZ 249810 The meaning is unknown to me. CK 2733373 This is neither new nor unknown. Dejo 23856 The origin of the fire is unknown. Archibald 1126687 The source of the fire is unknown. nadsat 805266 Smallpox was unknown to Native Americans. Source_VOA 307966 The reason she killed herself is unknown. CM 2274 A known mistake is better than an unknown truth. Zifre 239547 At present, the cause of the disease is unknown. CK 847235 Many great thinkers who were unknown while alive became famous after death. Source_Benedict_1921 1647967 Lonesome George, the last remaining tortoise of his kind, died of unknown causes. Spamster 43238 Sophie had been looking forward to getting another letter from the unknown sender. CK 275096 Although most islands in the ocean have been mapped, the ocean floor is generally unknown. CK