However, {HEAD ~ other halocarbons}, such as {TAIL ~ straight fluorocarbons} can be used 
such as
However , { HEAD ~ other halocarbons } , such as { TAIL ~ straight fluorocarbons } can be used
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH