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oh; ho; exclamation of surprise, admiration, etc.
hoo (owl call); toot (sound of a flute)
ほう、それは面白いおもしろいね。
Oh, that's interesting.
ほう、こんなことがあるとは。
Oh, I didn't expect this.
ほう、なかなかやるじゃないか。
Ho, not bad at all.