半瓶水响叮当

bàn píng shuǐ xiǎng dīng dāngbanpingshuixiangdingdang

1. lit. if you tap a half-empty bottle it makes a sound (idiom)
2. fig. empty vessels make the most noise
3. one who has a little knowledge likes to show off, but one who is truly knowledgeable is modest

Study it in Yanamino