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受第一机械工业部委托,由北京市农业机械局、河北省机械工业局主持于一九七五年十月十六日至二十一日在张家口市召开了农用挂车系列中的三、五、七吨挂
Entrusted by the First Ministry of Machinery Industry, the Beijing Agricultural Machinery Bureau and the Hebei Machinery Industry Bureau convened the third and fifth of the agricultural trailer series in Zhangjiakou City from October 16 to October 1975. , seven tons hanging