2017南通泰州一模数学 求解一道题2017南通一模的答案为啥选

求解一道题2017南通一模的答案为啥选  

Being attachedto the gift was a note on which he expressed his appreciation for our reception during his stay here.

这是个倒装句，原来语序为；

a note was being attachedto the gift 【on which he expressed his appreciation for our reception during his stay here】.定语从句不用看；

用被动进行表示同时关系，用Attached可能表示a note并没有当时看。