In different duration, the annual changes of occurrence frequency of heavy fog in Hefei area were different.

在不同持续时间内，合肥地区大雾出现频数的年变化不同。

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In different duration, the annual changes of occurrence frequency of heavy fog in Hefei area were different.

在不同持续时间内，合肥地区大雾出现频数的年变化不同。

youdao