Answer:
1) You have been invited by someone to the dinner today.
2) Your phone was found by someone on the top of the cupboard.
3) The chickens were fed by no one this morning.
4) The book will be written by the author next June.
Explanation:
First, identify the direct subject of this sentence. Remember to always change things in the independent clause. Then place the indirect object of the sentence at the beginning. Now, switch things around until they make the same meaning (except wordier), and voila - you are done.
Note: most of the time, passive voice is wordy, unclear, and hard to read. So stick with active voice, where you place the subject at the front of the sentence, for other writing.
Hope this helps! :)
