( ( ( ( ( ( The reason ) ( for this ) ) ( can ( be ( as follows ) ) ) ) : ) ( ( The customer ) ( requires ( a ( separate ( combustion ( air fan ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (NN reason)) (PP (IN for) (NP (DT this)))) (VP (MD can) (VP (VB be) (SBAR (IN as) (S (VP (VBZ follows))))))) (: :) (S (NP (DT The) (NN customer)) (VP (VBZ requires) (NP (DT a) (JJ separate) (NN combustion) (NN air) (NN fan)))) (. .)))
The reason for this can be as follows: The customer requires a separate combustion air fan.
(ROOT (S (NP (NNP Air)) (VP (MD can) (VP (VB be) (VP (VBN separated) (PP (IN into) (NP (JJ several) (NNS elements)))))) (. .)))