Thus, when a viewer views the exterior of the lamp generally in elevation, {HEAD ~ the cover} selectively displays {TAIL ~ different designs} to the viewer depending on the illumination state of the device 
selectively displays
Thus , when a viewer views the exterior of the lamp generally in elevation , { HEAD ~ the cover } selectively displays { TAIL ~ different designs } to the viewer depending on the illumination state of the device
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH