(IP (NP-SBJ (NP (PN 其)) (NP (NN 原因))) (VP (VC 是) (NP-PRD (CP (WHNP-1 (-NONE- *OP*)) (CP (IP (NP-SBJ (-NONE- *T*-1)) (VP (VV 显而易见))) (DEC 的)))))) arg0: *T*-1