Connecting structure and covering device for opening of building

A connecting structure, comprising:

• a first object;
• a second object connected to the first object;
• a first engaging member;
• and
• a second engaging member located between the first engaging member and the first object, wherein the first engaging member is located between the second engaging member and the second object;
• wherein a thickness of the second engaging member is defined as a first thickness;
• when a distance between the first engaging member and the first object is less than or equal to the first thickness, the first engaging member and the second engaging member are not movable relative to each other;
• when the distance between the first engaging member and the first object is greater than the first thickness, the first engaging member and the second engaging member are adapted to be moved relative to each other in a direction, moving the first object and the second object relative to each other at the same time;
• wherein the first engaging member has a hole, of which a width in the direction is defined as a first width;
• the second engaging member comprises a protrusion, of which a width in the direction is defined as a second width;
• the protrusion passes through the hole, and the second width is less than the first width, so that the protrusion is adapted to be moved in the hole in the direction, whereby, when the distance between the first engaging member and the first object is greater than the first thickness, the second engaging member is adapted to be moved relative to the first engaging member in the direction.