HSK 7-9
哼
hēng动
to groan; to snort; to hum; to croon
女孩哼着小曲整理旧照片。
Nǚ hái hēng zhe xiǎo qǔ zhěng lǐ jiù zhào piān.
The girl hummed a tune while sorting old photographs.
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Appears across levels (7-9) in the HSK 3.0 word list.