Yypl03 yog qhov ntsuas ntsuas ntsuas tau tsim raws li tus qauv "GB / T 4545-2007 cov khoom lag luam hauv iav thiab cov khoom iav thiab txheeb xyuas kev ntxhov siab sab hauv
Cov khoom lag luam.
Cov lus qhia tshwj xeeb: