Complete the story of the Bermuda Triangle with the past perfect simple or past perfect continuous form of the verbs in brackets. In December 1945, five military planes were on a training flight after they 1 (take off) from an airbase in Florida in the USA. The planes 2 (fly) for about an hour and they 3 (fly) about 300 miles when without warning, the navigational instruments on all the planes, which 4 (work) perfectly up to that point, suddenly stopped working. Radio contact was then lost. None of the planes or crew was ever seen again. The official explanation is that before they vanished, the planes 5 (fly) into an area of unusual magnetic activity. It is believed that this 6 (cause) their compasses and other equipment to malfunction. The planes were flying over the Atlantic Ocean near Bermuda and the story of the Bermuda Triangle was born. By the mid-1970s, sixteen more planes 7 (mysteriously/disappear) in the same area. And it appears that in almost all cases, the navigational equipment 8 planes disappeared. (stop) working just before the