1.We had to pay (custom) duties on the watches.我们必须为这些手表支付关税.
2.They were asked to write an (answer答案) of a poem of their choice.
pay duty on sth 付税···
custom duty 海关关税answer感觉并不合适啊也是。楼下的答案更合适：analysis 或appreciation，没有上下文联系，好像这两个都可以，个人觉得appreciation更贴切。