Also, {HEAD ~ the block} has {TAIL ~ the surface} of arcuate shape in cross section at least at a part of its side surface 
Also , { HEAD ~ the block } has { TAIL ~ the surface } of arcuate shape in cross section at least at a part of its side surface
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH