谁能帮我分析一下这个英语句子

Folded in the card was a piece of paper .
过去分词表被动，作表语。类似倒桩，＝a piece of paper was folded in the card
折叠在卡片里的是一张纸

Written on the card was a message （under the printed Happy Birthday）定语 --Buy yourself something nice with the cheque
过去分词表被动，作表语。类似倒桩，＝a message was written on the card
一条信息被写在卡片上印的生日快乐的字下面，写着：用支票给你自己买些好东西

Folded in the card was a piece of paper.
这句话感觉不像是倒装，里面的was不是表被动的，单纯的系动词做标语。可以理解成：
What was folded in the card was a piece of paper.
后面的就一样了。

倒装。a piece of paper was Folded in the card. a message was Written on the card.
望采纳

这是倒装结构，正确的语序应为 a piee of paper was folded in the car

fold的过去式，write的过去分词

我的英语是2级