【化学】以卤素为杂原子的环

dark rings around the eyes

keto group bound to rings other than six-membered aromatic rings

nitrogen-oxygen heterocycles having six-membered rings

annular rings

elastomeric O-rings

garage with rotary rings as means for transport

high-crown-drum method making bead-rings for pneumatic tyres

multi-phase synchronous motor having excitation without slip-rings