A lazy Susan is an addition to a table that is designed to assist in moving food from one person to another while dining. This is achieved through the use of a turntable  , which usually moves the food in a circle when it is pushed by those at the table. In this way, the food never has to be picked up and passed around the table. Instead, it remains in place on the lazy Susan. A lazy Susan may also be a part of a kitchen cabinet  . In this sense, the lazy Susan is a type of shelving unit within the cabinet that is able to turn around its axis  . One may turn the lazy Susan in order to find certain goods in storage. From the outside, a lazy Susan appears to be two cabinets that are located at a right angle   to each another. When one of these cabinets is pushed, however, both doors move and the lazy Susan is revealed inside. It is believed that Thomas Jefferson invented the lazy Susan in the 18th century, though it was called "dumbwaiter" at that time. It is said that Jefferson invented the lazy Susan because his daughter complained she was always served last at table and, as a result, never found herself full when leaving the table. Others believe that Thomas Edison was the inventor, as he is believed to have invented the turntable for his phonograph  . The turntable may have developed into the lazy Susan later. Regardless of who invented it, it wasn't until 1917 that the term "lazy Susan" was used in an advertisement for the invention. In Britain, however, the term "dumbwaiter" is still used rather than "lazy Susan". The reason for the naming of it is still a mystery. One theory is that it was named after either Jefferson's or Edison's daughter, both of whom were named Susan. The writer wrote the passage mainly to   _  .
discuss how the lazy Susan was named teach us how to make a lazy Susan introduce Thomas Edison's inventions tell us what a lazy Susan is and its origin