攻关
gōng guān · HSK 7
fig. to tackle a key problem
⚔️🚪 攻 attack + 关 pass/gate = storm the gate, tackle the tough problem
攻 (attack) + 关 (mountain pass/gate). Originally military: storming a strategic chokepoint. Now figurative for cracking a hard problem — research teams 攻关 a tough technical challenge.
攻 — 工 (gōng, phonetic) + 攵 (strike/action)
A semantic-phonetic compound: 攵 (a hand holding a stick) gives the meaning of striking or attacking, while 工 supplies the sound. Originally meaning to attack militarily, it later extended to 'work on' or 'study intensively,' as in 攻读.
关 — door 门 + simplified 关 inside
关 is the simplified form of 關. The traditional character showed a gate (門) with a bolt or crossbar inside, depicting a barred door — hence 'to close' or 'shut'. Meaning later extended to 'pass' (a guarded gate), 'barrier', and figuratively 'concern' or 'connection'.