(S (S (PP-SBJ (BASENP (NN 調査)) (IN は)) (COMMA 、) (VP (SBAR (S-NSBJ (VP (PP-OBJ (BASENP (NN 落雷)) (IN を)) (VP (VBV 受け) (VP (MD た))))) (INQT と)) (VP (VP (NN 結論) (VBV 付け)) (VP (MDV まし) (VP (MD た)))))) (PERIOD 。))
調査 は 、 落雷 を 受け た と 結論 付け まし た 。
An investigation concluded that it had been hit by lightning .