HSK 7-9
聚精会神
jùjīng-huìshénto concentrate one's attention (idiom)
学生们聚精会神地观察实验。
Xué shēng men jù jīng huì shén de guān chá shí yàn.
The students observed the experiment with complete concentration.
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Other HSK words sharing a character
Also free:
Appears across levels (7-9) in the HSK 3.0 word list.