{HEAD ~ Various kinds} of positive displacement dispensing pumps may be used in practicing {TAIL ~ the invention} 
used in practicing
{ HEAD ~ Various kinds } of positive displacement dispensing pumps may be used in practicing { TAIL ~ the invention }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL