Njerwa ndi zida zomangira zodziwika bwino, ndipo zimagwiritsidwa ntchito kwambiri m'magawo ambiri. Monga imodzi mwa mafupa omanga, kufunikira kwa njerwa kukukulirakulira pang'onopang'ono. Inde, njirayi ndi yosasiyanitsidwa ndi kugwiritsa ntchito makina opangira njerwa. Ndi ver
Palinso mitundu yambiri ya makina a njerwa pamsika, pakati pawo pali makina a njerwa otchedwa konkire block machine. Koma kodi mukudziwa zozindikiritsa makina oyika njerwa? Kodi mukudziwa zomwe zilembo za nambala ya njerwa zimayimira?