free maintenance period
maintenance free
免
免维护
免保养
永久免维护
不需维修
不需保养的
不需维护的
chrome free and formaldehyde free tannage
lead free and cadmium free
1150mm free standing last-stage steel blades
1-Diphenyl-2-picrylhydrazyl DPPH free radical
2-D free shear turbulent flows
3-D free curved surface
6-tetramethyl-1-piperidinyloxy free radical
a free floating sensing diaphragm