The classifying openings permit {HEAD ~ material} which is already smaller than the size of {TAIL ~ the openings} to fall therethrough, thereby bypassing the comminution apparatus 
The classifying openings permit { HEAD ~ material } which is already smaller than the size of { TAIL ~ the openings } to fall therethrough , thereby bypassing the comminution apparatus
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH