{HEAD ~ A frame} of a pair of glasses has {TAIL ~ a pair} of eye rims with front surface and nasal regions which are connected together by a bridge with a front surface and a nasal region 
has
{ HEAD ~ A frame } of a pair of glasses has { TAIL ~ a pair } of eye rims with front surface and nasal regions which are connected together by a bridge with a front surface and a nasal region
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH