Task: Pos Tagging
Input (English): Sentence: This reduces to the relationship : Af , where Af is the intercept at {{ zero }} thickness of the extrapolation of the slope indicated in eqn. ( 1 ) , Af is the thickness of the coating equivalent to the rounding off of the knife tip , Af is a straight line first approximation of this roundness , and the other symbols are equivalent to those of eqn. ( 1 ) . 
Word: zero
Output (English): NUM