All that can be said ______.

Please tell Tom not to leave the classroom unless he ______ that all the lights ______.

The Russian rocket designer has died. For many years, he ______ as an important assistant to the father of Soviet space program.  

---I didn’t go to Mary’s party last night because my car broke down.---You could have borrowed mine. I ______ it.

That piece of music sounds quite familiar. Who _____ the piano upstairs?