Occasionally, {TAIL ~ control} of {HEAD ~ the treating solution flow} in addition to that provided by the brush members is necessary 
Occasionally , { TAIL ~ control } of { HEAD ~ the treating solution flow } in addition to that provided by the brush members is necessary
OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH