{HEAD ~ The percent area A} of the plane in the slide surface is set in {TAIL ~ a range} of A≧50% 
is set in
{ HEAD ~ The percent area A } of the plane in the slide surface is set in { TAIL ~ a range } of A≧50 %
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH