1. The janitors clean the building at night.
The buildings cleaned by the janitors at night.
2. Window washers wash the windows.
The windows
wash
3. A window washer is washing a window right now.
A window
wash
by window washers.
4. The security guard has checked the offices.
The offices
check
by a window washer right now.
-
by the security guard.
5. The security guard discovered an open window.
An open window
discover.
by the security guard.