了如指掌

瞭如指掌
liǎorúzhǐzhǎng
variant of 了如指掌 liǎorúzhǐzhǎng

CEDICT

to know like the back of one's hand

Wiktionary

本指天下事如掌中物，易于了解。语本《论语．八佾》：「『知其说者之于天下也，其如示诸斯乎？』指其掌。」后比喻对事情了解得非常清楚。《荡寇志．第三三回》：「虽未出兵打仗，而战阵攻取之法，瞭如指掌。」也作「了如指掌」、「了若指掌」、「瞭若指掌」。

重編國語辭典

对情况非常清楚、了解

維基詞典

Homographs

了如指掌 liǎorúzhǐzhǎng
  1. to know sth like the back of one's hand (idiom)
  2. to know (a person, a place etc) inside out

Entry Composition

=1 了 liǎo
  1. to finish
  2. (used with 得 dé or 不 bù after a verb to express (im)possibility, as in 忘不了 wàngbuliǎo "cannot forget")
  3. (literary) (usually followed by a negative such as 无 wú or 不 bù) completely (not); entirely (not); (not) in the least
  4. to understand clearly (variant of 了 liǎo)
=1 了 liǎo
  1. (of eyes) bright
  2. clear-sighted
  3. to understand clearly
2 如 rú
  1. as
  2. as if
  3. such as
3 指 zhǐ
  1. finger
  2. to point at or to
  3. to indicate or refer to
  4. to depend on
  5. to count on
  6. (of hair) to stand on end
4 掌 zhǎng
  1. palm of the hand
  2. sole of the foot
  3. paw
  4. horseshoe
  5. to slap
  6. to hold in one's hand
  7. to wield