过去分词enclosed可作名词，前面加定冠词：We believe you will find the enclosed interesting. 我们相信你们对所附之件会感兴趣。
5.Requirements
requirement 表示需要时，常用单数，后接介词of： We have noted your requirement of samples and catalogues.我们已经注意到你们需要样品和商品目录。
表示需要的货物或需要量时常用复数，后接介词for或of： We can meet your requirements for Walnut meat.我们可以满足你方对核桃仁的需要。Please let us know your annual requirements of Walnuts.请告知你方对核桃的年需求量。
注意：表示满足需要，除meet外，还可以用satisfy， fill， supply 等动词。
6.Promote
to promote both business and friendship促进业务和友谊；
可替代的用法是：to promote friendship as well as business .
7.trade in 和trade with
in our trade with customers in the Asian-African countries我们在同亚非国家的客户进行贸易时；
trade 做动词用时，表示“从事贸易，做生意，经营”。
注意：和某人做贸易接with， 经营某项商品接in. 如：They trade mainly in cotton piece goods.他们主要经营棉布。