They let off At their friend and is air .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 They)) (VP_4 (ATVP_1 (ATVP_2 (ATVP_0 (VB_0 let) (PRT_0 (RP_0 off))) (PP_0 (IN_1 At) (NP_2 (PRPDOLLAR_0 their) (NN_0 friend)))) (CC_0 and)) (VP_5 (VBZ_0 is) (NP_2 (NN_3 air))))) (DOT_0 .)))