the navy should came up under boulders .
(ROOT_0 (S_0 (ATS_3 (NP_1 (DT_0 the) (NN_2 navy)) (VP_4 (MD_0 should) (VP_1 (ATVP_3 (VBD_2 came) (PRT_0 (RP_0 up))) (PP_0 (IN_1 under) (NP_4 (NNS_1 boulders)))))) (DOT_0 .)))