Polar questions are often constructed by repetition of the verb in positive and negative forms: e.g.Tibe nada ni-nada? [2SG necessary NEG-necessary] 'Do you need?' This pattern is a loan from Chinese.
Source: Jabłońska 1957: 167
Source: Perekhvalskaya 2008: 263
Source: Jabłońska 1957: 167
Source: Perekhvalskaya 2008: 226