Ese imigozi yo mu mutwe ikoreshwa mu gupima irasaba imyobo yo mu mutwe ikoreshwa mu gupima irangi?

Mbere yo gukoresha riveti ifunguye yo gukurura umutwe, ni ngombwa kubanza gukora umwobo wo gukurura ku isahani, bitabaye ibyo bizoroha kuba ibingana nyuma yo gukurura.