这段话是什么中文意思?David and Xiaoyan arrived at the airport in good

这段话是什么中文意思?
David and Xiaoyan arrived at the airport in good time.After checking in at the British Airways desk,they had their boarding passes checked,put their bags through X-ray machine and went through the passport control on their way to the departure lounge.They didn't have anything to eat because they would eat on the plane,but they had a coffee and then they looked round the shops.Xiaoyan bought something for Mary,but David didn't buy anything.Then they went to the gate.They had about 20 minutes to wait before embarking.Suddenly David realized that he hadn't got his camera with him.They went back and looked everywhere to see where he could have lost it---- in the shops,in the cafe,at the X-ray machine,at the passport control and at the checking-in desk,but nobody had seen it."I must have left it in the cafe,"said David,"I should have put it in my bag.I suppose someone must have walked off with it!"