dòng洞cave, grotto; ravine; holeHSK 5 · Frequency 4.5Meanings洞; hole; cave; penetrateRelated words洞穴洞仙洞鉴洞察洞察力洞窟洞洞鞋洞悉洞庭洞见洞房花烛洞开Example sentences空洞理论毫无意义。工人正在修补漏洞。洞穴里很黑。