敲釘鑽腳 qiāo dīng zuān jiǎo

DEFINITIONS

  1. to make doubly sure (idiom)

CHARACTERS

敲 qiāo
HSK 4
strike, beat, pound, hammer; rap
釘 dīng nail, spike; pursue closely
鑽 zuān drill, bore; pierce; diamond
腳 jiǎo foot; base, leg, foundation