Answer:
Roof- is the top covering of a building, including all materials and constructions necessary to support it on the walls of building or on uprights, providing protection against the rain, snow, sunlight, extremes of temperature and wind.
Wall- to support roofs, floors and ceilings; to enclose a space as part of the building envelope along with a roof to given buildings; and to provide shelter and security.
Floor- can support the expected load.
Door- are generally used to separate interior space (closets, rooms, etc.) for convenience, privacy, safety and security reason.
