了如指掌 (liǎo rú zhǐ zhǎng) | Meaning: to know sth like the back of one's hand (idiom) | Chinese Idiom with Pinyin & Origin

obvious at a glance (idiom)一目了然yī mù liǎo rán

to be very clear about sth (idiom)一清二楚yī qīng èr chǔ

lit. to see sth as clearly as one sees a blazing fire (idiom) · fig. to grasp the situation thoroughly洞若观火dòng ruò guān huǒ

to understand thoroughly · to see beyond the facade · to see through (sb)看透kàn tòu

know yourself, know your enemy (idiom, from Sunzi's "The Art of War")知己知彼zhī jǐ zhī bǐ

lit. as if enumerating one's family valuables (idiom) · fig. to be very familiar with a matter如数家珍rú shǔ jiā zhēn

to know sth like the back of one's hand (idiom) · to know (a person, a place etc) inside out