Free net adjustments mainly fall into three kinds: the commonly used rank-defect network adjustment, the quasi-stable adjustment and the (norm) weighted rank-defect adjustment, of which the last one is the general form. This essay argues that s (1) the results obtained from these adjustments can be transformed one another without calculating d-order inverse matrix, (2) the solutions derived from them, just like that gained from the classical free net adjustment, are unbiased. Among them xr
is the best unbiased estimation, xs
is partly best and xp
is the best with weight.