Sentence:  It is made up of tumbling , which might be said to start with a somersault , run through such stunts as headstands , handstands , cartwheels , backbends , and culminate in <WSD>nearly</WSD> impossible combinations of aerial flips and twists and apparatus work . 
Meaning of the word marked with <WSD> tags:  (of actions or states) slightly short of or not quite accomplished; all but