so by a air the classes , . <apostrophe><apostrophe>
(ROOT_0 (S_0 (ATS_2 (ATS_3 (PP_2 (ATPP_0 (ATPP_0 (RB_1 so) (IN_1 by)) (NP_5 (DT_0 a) (NN_2 air))) (NP_6 (DT_0 the) (NNS_1 classes))) (COMMA_0 ,)) (DOT_0 .)) (APOSTROPHE_0 <apostrophe><apostrophe>)))