{HEAD ~ A plurality} of connecting lines are provided {TAIL ~ that couple a respective pairs} of gas input and gas output lines 
are provided
{ HEAD ~ A plurality } of connecting lines are provided { TAIL ~ that couple a respective pairs } of gas input and gas output lines
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH