Iivalvu ezininzi eziqhelekileyo ezisetyenziswa kwimibhobho yoshishino, iivalvu zebhola zinelona luhlu lubanzi lokusetyenziswa, nokuba ngamanzi, i-oyile, igesi okanye imibhobho yemidiya eqhelekileyo okanye iimeko ezirhabaxa zokusebenza eziqulathe amasuntswana anobulukhuni obuphezulu, nokuba bubushushu obuphantsi, ubushushu obuphezulu, okanye i-corrosion. ubume bendalo, wena...
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