英语翻译Discharge at loading port,the Seller at his expenses sha

英语翻译Discharge at loading port,the Seller at his expenses shall determine the weight and the Quality of each shipment of Copper Cathodes Cu by SGS.The weight of Copper cathodes as ascertained and certified together with SGS analysis Certificate shall be the basis of the provisional invoice.第一句话我不理解的，是determine的意思是什么。第二句话：The weight of Copper cathodes as ascertained and certified together with SGS analysis Certificate shall be the basis of the provisional invoice.我不理解的是，为什么重量的检测，是基于“临时发票”？