The VP 放本書 (fàng běn shū/ putting down a book) requires a PP as the locative argument. Therefore, we can’t say 我放本書 (wǒ fàng běn shū) without any location. It has to take a PP which can be either pre-verbal, i.e. 我在桌上放本書 (wǒ zài zhuō shàng fàng běn shū/ I put a book on the desk.) or post-verbal, i.e. 我放本書在桌上 (wǒ fàng běn shū zài zhuō shàng/ I put a book on the desk.)
