a throttle valve disposed in an intake passage of said internal combustion engine for controlling {HEAD ~ the area} of {TAIL ~ opening} of said intake passage 
of
a throttle valve disposed in an intake passage of said internal combustion engine for controlling { HEAD ~ the area } of { TAIL ~ opening } of said intake passage
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH