Njerwa ndi bwino - zomangira zomangamanga, ndipo zimagwiritsidwa ntchito kwambiri m'minda yambiri. Monga limodzi la mafupa omanga, kufunikira kwa njerwa kumakulitsa pang'onopang'ono. Inde, njirayi ndiyosagwirizana ndi kugwiritsa ntchito makina opanga njerwa. Ndi ver