An intake air duct serving as {TAIL ~ a passage} for supplying air to {HEAD ~ an engine}, the intake air duct comprising: 
An intake air duct serving as { TAIL ~ a passage } for supplying air to { HEAD ~ an engine } , the intake air duct comprising :
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH