Task: Pos Tagging
Input (English): Sentence: The K factor , a term used to denote the rate of heat transmission through a material ( {{ B.t.u./sq. }} ft. of material/hr./*0F./in. of thickness ) ranges from 0.24 to 0.28 for flexible urethane foams and from 0.12 to 0.16 for rigid urethane foams , depending upon the formulation , density , cell size , and nature of blowing agents used . 
Word: B.t.u./sq.
Output (English): X