`` to classes and the skin should stand heavy boulders in a back sweater .
(ROOT_0 (S_0 (ATS_3 (ATS_4 (ATS_0 (TICK_0 ``) (PP_2 (TO_0 to) (NP_3 (NNS_1 classes)))) (CC_0 and)) (S_1 (NP_0 (DT_0 the) (NN_2 skin)) (VP_5 (MD_0 should) (VP_1 (ATVP_2 (VB_0 stand) (NP_4 (JJ_1 heavy) (NNS_1 boulders))) (PP_2 (IN_0 in) (NP_6 (ATNP_1 (DT_0 a) (JJ_1 back)) (NN_1 sweater))))))) (DOT_0 .)))