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whistle (sound made with the lips)
口笛を吹いて犬を呼んだ。
I whistled to call the dog.
彼女の口笛の上手さに驚いた。
I was surprised at how well she could whistle.
映画のシーンで主人公が口笛を吹きながら路地を歩いていた。
In the film scene, the protagonist was walking through an alley whistling.