a rotating photosensitive drum for forming {TAIL ~ a toner image} on {HEAD ~ a cylindrical surface} thereof 
a rotating photosensitive drum for forming { TAIL ~ a toner image } on { HEAD ~ a cylindrical surface } thereof
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH