I water flowers every day
flowers(are watered by me ) every day
2.He often makes Mrs Green laugh
Mrs Green is often( made to ) laugh by him
3.They can finish the work on time
The work can( be finished ) on time
4.The children are planting trees near the river
Trees( are being planted ) near the river by the children
5.John read the book yesterday
The book( was read ) by John yesterday
6.We can see lots of information on the computer.
Lots of information( can be seen ) on the computer
7.She often hears Peter sing in the next room
Peter(is ) often( heard to sing ) in the next room
8.They built the bridge three years ago
The bridge( was built ) by them three years ago
被动语态的结构：助动词be +动词的过去分词.（ 要 注意时态哦）
祝你假期愉快!加油!不明白再问!