{HEAD ~ The processing process} of {TAIL ~ the recessed hole} in the box end of the wrench is also complicated  
{ HEAD ~ The processing process } of { TAIL ~ the recessed hole } in the box end of the wrench is also complicated
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH