1,the house are cleaned everyday

2,this computer is exported to seventy different countries

3,a whistle would be blown if there is an emergency

4,two million books are sent to america every year

1/We clean the house every day. è

--> the house cleaned by us every day.

2/ We export this computer to seventy different countries. è

--> this computer exported to seventy different countries by us.

3/ Someone will blow a whistle if there is an emergency. è

--> a whistle had blown if there is an emergency.

4/ They send two million books to america every year.

--> two milion books sent to america every year.