80. A pipe conveying sewage from plumbing system of a single building to common sewer is called-
ব্যাখ্যা: ব্যাখ্যা: Main sewer as the primary pipeline in a sewerage system to which all the branching pipes carrying sewage from different location. Submain sewer means a city or privated owned sewer pipe designed to convey sewage from two or more building laterals to a main sewer.