1. Ua tib zoo saib seb puas yog tag nrho cov khoom sib kis ntawm lub crane, xws li rubeys, bearings thiab cov yeeb nkab groove sib txuas, ua suab nrov txawv txav (cov khoom no yuav tsum tsis tu ncua nrog cov roj los yog roj lubricating rau kev ua haujlwm), yog tias pom, koj yuav tsum tam sim ntawd. tshawb nrhiav txhua qhov Yog tias nws tsis yog ...
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