【生活】空心的

nitrogen-oxygen heterocycles having six-membered rings

be hell-bent on having one's own way

ether of polyoxyalkylenes having mixed oxyalkylene groups

drawing-board having means for clamping sheets of paper

piston having ring-shaped inserts

dc transformer having mechanical contacts

hobbing with the tool having the same profile as the tooth, teeth of a crown, bevel gear

starting apparatus having pull-cords