If ((, A, ) is a measure space, by means of an example, show that there may

If ((, A, μ) is a measure space, by means of an example, show that there may be subsets M ( N, where N are null sets in A, with M ( A. (If it so happens, however, that for every M ( N for every null N ( A, then M ( A, we say that A is complete with respect to μ.)