Our foreign trade policy has always been based on equality and mutual benefit and exchange of needed goods.
我们的对外贸易政策一向是以平等互利、互通有无为基础的。
the necessary method of study is to group the relevant material and to take note of all possible variant forms and conditions.
应采取的研究方法是,把有关各方面的材料汇集起来,同时注意任何可能出现的异常情况和条件。