From Li Hua's Tang-dynasty elegy 《吊古战场文》: 人或有言，将信将疑 — mourners half-believe, half-doubt tales of the ancient battlefield. The 将…将… pattern means 'now... now...' (simultaneously both).
grammar
The 将…将… construction here is a classical parallelism equivalent to 又…又… — 'both believing and doubting.' This is not the modern 将 meaning 'will / in the future.'
