HSK 7-9
潜入
qiánrù动
to submerge; to infiltrate; to steal into
记者悄悄潜入废弃工厂。
Jìzhě qiāoqiāo qiánrù fèiqì gōngchǎng.
The reporter quietly slipped into the abandoned factory.
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Appears across levels (7-9) in the HSK 3.0 word list.