[Q]: How does the sentence end?

The mechanic quickly diagnosed the problem with the muffler but couldn't figure out what was wrong with the alternator, because the problem with the 

[A]: alternator was rare.


[Q]: How does the sentence end?

After the wood bridge collapsed in Rome killing right people it was replaced with a metal one, the 

[A]: wood was unstable.


[Q]: How does the sentence end?

The guitar that I bought played better than the violin, because the 

[A]:
violin was very old.