n.空白；空隙；腔隙
Fill up a lacuna in one's knowledge 填補(bǔ)知識(shí)上的空白。
His long reticence temporarily distracted attention from a bigger lacuna. 他始終保持沉默，分散了人們對(duì)一個(gè)更大缺漏的注意力。
There was so much very deep lacuna in his crude big hands. 粗糙的大手上一道道很深的裂口。
