感叹词，hello变体。

1. That in turn is related to halloo, a cry to urge on hunting dogs.

而hallo则又与halloo有 联系, Halloo乃指敦促猎狗时的叫声,其历史又可上溯至1700年.

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2. Do not halloo till you are out of the wood.

未走出森林之前先别欢呼.

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3. He gave a great halloo but no one heard him.

他大声打了个招呼,但没有人听见.

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4. Do not halloo until you are out of the woods.

(谚)未出险境,先别高兴.

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5. Don't halloo till you are out of the wood.

未走出森林前别欢呼,别高兴得太早.

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