{HEAD ~ The polyalkylene glycol} must have {TAIL ~ a relatively low molecular weight}, preferably below about 2000 
have
{ HEAD ~ The polyalkylene glycol } must have { TAIL ~ a relatively low molecular weight } , preferably below about 2000
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH