Many strange new means of transport have been developed in our century, the strangest of them being, perhaps, the hovercraft. In 1953, a former（在前的） electronics（电子学） engineer in his fifties, Christopher Cockerel, who had turned to boatbuilding on the Norfolk Boards, suggested an idea on which he had been working for many years to the British government and industrial（工业的） circles. It was the idea of supporting a craft（工艺） on a pad（垫） or cushion of low pressure（压力） air, ringed with a curtain（帘） of high pressure（压力） air. Ever since（后来）, people have had difficulty（ 困难） in deciding whether（ 是否） the craft（工艺） should be ranged among ships, planes, or land vehicles, for it is something in between a boat and an aircraft（飞机）.