(IP (ADVP (AD 但)) (NP-SBJ (-NONE- *pro*)) (VP (NP-TMP (QP (CD 许多)) (NP (NN 时候))) (ADVP (AD 却)) (VP (VV 受用无穷))))
ARG1: *pro* ARGM-ADV: 却 ARGM-TMP: 许多 时候 ARGM-DIS: 但 REL: 受用无穷