How can the definers be sure we will know without being told that a man-about-town is never a woman?
( How ( ( ( can ( the definers ) ) ( be ( sure ( we ( will ( know ( without ( being ( told ( that ( ( a man-about-town ) ( ( is never ) ( a woman ) ) ) ) ) ) ) ) ) ) ) ) ) ? ) )
(ROOT (SBARQ (WHADVP (WRB How)) (SQ (MD can) (NP (DT the) (NNS definers)) (VP (VB be) (ADJP (JJ sure) (SBAR (S (NP (PRP we)) (VP (MD will) (VP (VB know) (PP (IN without) (S (VP (VBG being) (VP (VBN told) (SBAR (IN that) (S (NP (DT a) (NN man-about-town)) (VP (VBZ is) (ADVP (RB never)) (NP (DT a) (NN woman)))))))))))))))) (. ?)))
How can one be sure a man was not born a woman? It is very deceiving  unless someone would tell you. 
( ( How ( ( ( can one ) ( be ( sure ( ( a man ) ( ( was not ) ( born ( a woman ) ) ) ) ) ) ) ? ) ) ( It ( ( ( is ( very deceiving ) ) ( unless ( someone ( would ( tell you ) ) ) ) ) . ) ) )
(ROOT (S (SBARQ (WHADVP (WRB How)) (SQ (MD can) (NP (PRP one)) (VP (VB be) (ADJP (JJ sure) (SBAR (S (NP (DT a) (NN man)) (VP (VBD was) (RB not) (VP (VBN born) (NP (DT a) (NN woman))))))))) (. ?)) (NP (PRP It)) (VP (VBZ is) (ADJP (RB very) (JJ deceiving)) (SBAR (IN unless) (S (NP (NN someone)) (VP (MD would) (VP (VB tell) (NP (PRP you))))))) (. .)))