Most of the sandstorms that had swept China last year originated from foreign land，a Chinese official in charge of desertification control said on Monday.And the invasions(入侵) could partly explain the frequent sandstorms in the country in recent years despite its achievements in desertification control. Since the start of last spring，the north and northwestern Chinese regions had been hit by 17 sandstorms，of which，a dozen came from foreign land.

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