( ( Describe ( how ( ( simple machines ) operate ) ) ) . )
(ROOT (S (VP (VB Describe) (SBAR (WHADVP (WRB how)) (S (NP (JJ simple) (NNS machines)) (VP (VBP operate))))) (. .)))
Describe how simple machines operate.
(ROOT (S (S (NP (DT A) (JJ complex) (NN machine)) (VP (VBZ is) (VP (VBN described) (PP (IN by))))) (: :) (S (NP (PRP it)) (VP (VBZ is) (VP (VBN made) (PP (IN of) (NP (QP (JJR more) (IN than) (CD one)) (JJ simple) (NN machine)))))) (. .)))
A complex machine is described by: it is made of more than one simple machine.