钻故纸堆 zuān gù zhǐ duī

DEFINITIONS

  1. to dig into piles of outdated writings (idiom); to study old books and papers

CHARACTERS

钻 zuān
HSK 6
drill, bore; pierce; diamond
故 gù
HSK 3
ancient, old; reason, because
纸 zhǐ
HSK 2
paper
堆 duī
HSK 5
heap, pile, crowd; pile up