{HEAD ~ A borohydride}, as {TAIL ~ e.g. an alkaline earth metal} or preferably an alkaline metal borohydride, such as potassium or sodium borohydride, is the least preferred reducing agent 
{ HEAD ~ A borohydride } , as { TAIL ~ e.g. an alkaline earth metal } or preferably an alkaline metal borohydride , such as potassium or sodium borohydride , is the least preferred reducing agent
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH