In many locations, properly-located and legally constructed facilities, such as a single fire ring, should be left.

在许多场所，应当保留适当的设置和合法建造的设备，比如一个单个的行军灶。

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A single spark can start a prairie fire.

星星之火，可以燎原。

《新英汉大辞典》

The single spark that started the prairie fire suggests the answer.

引发燎原之火的火花暗示了答案。

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Following Scottish Parliament legislation, there will also be a new single fire service for Scotland.

BBC: MSPs urge police bosses to end power struggle

The consultation, to get under way next month, will outline three options for fire and police services - eight services with enhanced collaboration between them, a regional structure with fewer boards, or a single service for fire and a single force for police.

BBC: Scottish police force merger plan outlined

Shortly afterwards, police heard a single gunshot as fire began to spread through the cabin.

BBC: Christopher Dorner: LA police end hunt after body found