double fixed valve

fixed distance frame of steel bar

fixed distance parting mechanism

air line distance

double line AFS

double line cutter

double line method

Double line of atomic emission spectroscopy

Double Line Railway

Double line river

Double line shield

double line swivel pen

double line type

double line voltage synthesis

double line whole-hole box bridge

film-mulching of double line width ridge

double blind double dummy

Double blind double dummy randomized controlled clinical trial

Double Chambers and Double Layers