HSK 5
以
yǐ介（连）
to use; by means of; according to; in order to; because of; at (a certain date or place); abbr. for Israel 以色列
我们以实际行动保护环境。
Wǒ men yǐ shí jì xíng dòng bǎo hù huán jìng.
We protect the environment through concrete action.
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Appears across levels (5（7-9）) in the HSK 3.0 word list.