Ntau ntau yam khoom siv hauv tsev thiab, tshwj xeeb, cov tshuab ntxhua khaub ncaws tau nthuav tawm ntawm kev lag luam hauv tsev. Qee lub sij hawm nws nyuaj rau cov neeg siv khoom kom nkag siab txog cov yam ntxwv ntawm cov qauv thiab ua qhov kev xaiv zoo. Tsis ntev tas los no, Hoover cov khoom lag luam tau tshwm sim hauv khw muag khoom. Kev tshuaj xyuas cov tshuab ntxhua khaub ncaws, txawm tias qhov no, twb muaj, tab sis tsis ntau npaum li peb xav tau