10. The Benton Horde, a priceless collection of ancient Roman silver, (1)... from its display cabinet in the British Museum. At today's emergency press conference, the Museum director John Clive said, that according to his theory, the treasures (2)... by a professional gang on behalf of a specific collector. The matter is that the stolen silver (3) ... very well-known and it (4)... on the open market. Ten museums (5)... in the last six months and the number (6) steadily over the last few years. The Benton Horde (7) of Britain's most important collections of Roman silver. It (8) undiscovered for almost sixteen centuries beneath a Sussex field until it (9)... incidentally in 1926. 1) A was disappearing B was disappeared C has disappeared D had been disappeared