HSK 7-9
夯实
hāngshí动
to tamp; to ram (earth etc)
工人反复压土夯实路基。
Gōng rén fǎn fù yā tǔ hāng shí lù jī.
The workers repeatedly compacted the earth to firm up the roadbed.
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Appears across levels (7-9) in the HSK 3.0 word list.