Miàn / duì / zhè / ge / fù / zá / de / àn / jiàn / ， / diào / chá / rén / yuán / xū / yào / cháng / shí / jiān / míng / sī / 。

面对这个复杂的案件，调查人员需要长时间冥思。

Faced with this complex case, the investigators needed to think deeply for a long time.