Change the sentences from Active Voice to Passive Voice

1)the sweets had been eaten ,when i came home2)This book was written in 19th century 3)A number  of important experiments has bing made in this laboratory4)A new president is elected by people every four years in the USA5)He will be operated by  the doctor in a week 6)Streets are bing cleaned by the workers from rubbish 7)Very delicious food was bing made by my mother ,when i came home 8)This program can be used in my internet project 9) Two foreign languages are studied by our pupils