45. Vim li cas cov kav hlau yuav tsum tau ntxuav tam sim tom qab ntxuav cov kua qaub?

Tom qab muab tshem tawm los ntawm cov kua txiv hmab txiv ntoo, cov kav hlau yuav tsum tau muab yaug nrog dej tam sim ntawd txhawm rau tiv thaiv cov teeb meem hauv qab no: (1) Nws txwv tsis pub cov kua txiv hmab txiv ntoo los ntawm kev txuas ntxiv mus rau cov yeeb nkab nto; (2) Nws tiv thaiv hlau ntsev adhering rau cov yeeb nkab nto los ntawm oxidizing rau hauv hlau ntsev (trivalent hlau) uas nyuaj rau tshem tawm thaum raug oxygen, xws li kev hloov ntawm ferrous sulfate rau ferric sulfate; (3) Nws txo qhov tsim ntawm zinc residue; (4) Nws pab txhim kho qhov zoo ntawm galvanized txheej ntawm galvanized steel kav thiab txo los yog tshem tawm cov txheej tsis tau.