ADJUSTABLE SUPPORTING STRUCTURE

This disclosure provides a supporting structure for laying a cover panel for covering a carriage. The structure includes a first edge member disposed at a side edge of the cover panel configured to be laid flat; a first sealing member disposed partially to a bottom of the first edge member, the first sealing member comprising at least two tight units that are deformable to form a sealing contact with top edge of the carriage; a second edge member disposed to an inner side edge of the carriage, the second edge member comprising a groove on top and a protrusion portion at side towards interior of the carriage; and a second sealing member disposed at the groove to support the first edge member with a tight sealing contact between the first edge member and the second edge member.