Umcengezi ngaphansi kwetafula ubhekisa kumcengezi ofakwe ngaphansi kwezansi, kanti itafula likhulu kancane kunomcengezi. Kunezindlela ezimbili zokufaka, eyodwa ukuvula izimbobo onqenqemeni olungaphandle lwethangi lamanzi, omunye ukuvula izimbobo ngqo emaphethelweni angaphakathi ethangi lamanzi....