The propped block has {TAIL ~ several horizontal propped surfaces} on the bottom, which are formed at {HEAD ~ different heights} with slopes formed in between 
The propped block has { TAIL ~ several horizontal propped surfaces } on the bottom , which are formed at { HEAD ~ different heights } with slopes formed in between
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH