了然于胸 liǎo rán yú xiōng

DEFINITIONS

  1. to be well aware of sth
  2. to understand clearly

CHARACTERS

了 liǎo
HSK 1
to finish; particle of completed action
然 rán
HSK 2
yes, certainly; pledge, promise
于 yú
HSK 3
in, on, at; go to; surname
胸 xiōng
HSK 5
breast, bosom, chest; thorax