Thousands of birds fly back to the north in spring.

成千上万的鸟儿在春天飞回北方。

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Yanhe spring karst water system is one of the famous springs in North China.

山西省延河泉岩溶水系统是我国北方岩溶大泉之一。

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Yanhe spring karst water system is one of the famous springs in North China.

山西省延河泉岩溶水系统是我国北方岩溶大泉之一。

youdao