If the concrete is poured while the ground is wet, it will not form a solid foundation  If the concrete does not form a solid foundation, it will either settle unevenly or crack
So if the concrete settles evenly, either it was poured while the ground was dry or it will crack
The film will not be properly exposed if the camera is not working properly. If the film is not properly exposed, then the photograph will be either blurred or dark. So if the photograph is not blurred, either the camera is working properly or the photograph will be dark.