We can't identify the writer of the poem
The writer of the poem can't be identified.
They clean the windows every week.
The windows are cleaned every week.
They might have held the first World Cup in Brazil.
The WC might have been held...
They're following us.
We are being followed
Mary Shelley wrote the novel Frankenstein.
The novel Frankenstein was written by Mary Shelley.
People eat 40 million hamburgers every day.
40 million hamburgers are eaten every day.
They planted this tree in the 19th century.
It was planted
You ought not to waste your money on stupid things.
Your money ought not to be wasted on stupid things.
They don't allow smoking on planes.
Smoking is not allowed
They were doing experiments with Covid when somebody dropped the test tube!
were being done / was dropped
A guide will take you to your seat.
You will be taken to your seat by a guide.
The boy used to kill spiders.
Spiders used to be killed
My grandmother had been mixing the cake for several minutes when she burnt the cookies.
The cake had been being mixed / the cookies were burnt
They had eaten the pizza by the time we arrived.
The pizza had been eaten