like: thấu kính lõm
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Composite Words Listening Comprehension Oxford Topics Duolingo Topics 315 Activities
BEGINNER LEVEL
exact:
VNEN 
thấu kính lõm * ☊ 
concave lens * ☊
[ thấu ] : (1) to pass, penetrate, get through, understand; (2) to mix; to collect, gather
[ kính ] : (1) to (show) respect; (2) glass, (eye)glasses
[ lõm ] : concave, sunken
[ kính ] : glasses