The precondition of doing part time jobs is to fulfill one's primary occupation first.

做兼职的前提是应先做好自己的本业。

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Golding's renown as an art historian has obscured the fact that he considered painting his primary occupation.

WSJ: John Golding | Cubism's Vasari | By Elizabeth Cowling

This combined art and social practice is still the primary occupation of women in the village who create distinctive tablecloths, napkins and show pieces while sitting together and talking in the narrow streets or on covered patios.

UNESCO: Lefkara Laces or Lefkaritika