To account for such an escape of wh-phrase, two derivational theories have been generally adopted, those being PF Deletion Theory (Ross, 1969) and LF Copying Theory (CLM, 1995) respectively 1 .
sluicing in Mandarin Chinese is even more complicated since an argument-adjunct asymmetry in this wh-in-situ language is frequently demonstrated by shi-support, and little attention has been given to the point in the current related literature 2 .