The three teams of A, B and C all conduct field training from A to B. At 6:00 in the morning, A and B set off from A together. Team A walks 5 kilometers per hour, Team B walks 4 kilometers per hour, and Team C walks 4 kilometers per hour. The team starts from A at 8:00 in the morning, and at 6:00 in the evening, both teams A and C arrive at B at the same time, then at what time in the morning does it take for C to catch up with B?
甲乙丙三个小分队都从A地到B地进行野外训练，上午6时，甲乙两个小队一起从A地出发，甲队每小时走5千米，乙队每小时走4千米，丙队上午8时才从A地出发，傍晚6时，甲丙两队同时到达B地，那么丙队追上乙队的时间是上午多少时．
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