以下英语句子为啥有三个动词在句中？这是哪种句型，请老师从语法角度解释下。谢谢。

Question

The documents actually used in a transaction depend on the requirements imposed by both the importing and the exporting countries.

Answer 1

The documents actually (后置定语used in a transaction) depend on the requirements (后置定语imposed by both the importing and the exporting countries).
句子的谓语是depend on
其他两个动词都是非谓语动词结构，作后置定语。

这个句子就是个简单句，加了两个后置定语。
句意:交易中实际使用的单据取决于进口国和出口国的要求。