Upon completion of short-term work tasks after entry, if the work residence permit is still valid, extension applications are not allowed. However, if the individual is intending to be employed by a domestic employer, they can apply for a work permit with the relevant documents to the labor department during the validity period of the residence permit, following the procedures outlined in the "Rules for the Administration of Employment of Foreigners in China." The labor department issues a work permit and employment certificate to qualified individuals.