`` a classes of higher was jerked .
(ROOT_0 (S_0 (ATS_3 (ATS_1 (TICK_0 ``) (NP_1 (NP_6 (DT_0 a) (NNS_1 classes)) (PP_0 (IN_1 of) (NP_6 (JJR_0 higher))))) (VP_3 (VBD_1 was) (VP_2 (VBN_0 jerked)))) (DOT_0 .)))