30th, Lub Rau Hli, 2016, Zheng Heng tau tuav nws lub rooj sib tham txhua hli ntawm Qhov Teeb Meem thiab Kev Tshaj Tawm Tshaj Tawm.Muaj 6 qhov teeb meem 1 lub tswv yim tso tawm, uas suav nrog "Kev Kho Tshuab", "Txiav Lubricant Tshem Tawm", "Electric Standardization of Pressure ...
Nyeem ntxiv