本底调查 běn dǐ diào chá

DEFINITIONS

  1. background investigation

CHARACTERS

本 běn
HSK 1
root, origin, source; basis
底 dǐ
HSK 4
bottom, underneath, underside
调 diào
HSK 3
transfer, move, change; tune
查 chá
HSK 3
investigate, examine, seek into