I only realized how dangerous the situation had been when I got home.

=> Only (a)  

It wasn't until last week that the Agriculture Minister admitted defeat.

=> Only (a)  

I understood Hamlet only after seeing it on the stage.

=> Only (a)  

They didn't get round to business until they had finished eating.

=> Only (a)  

They had to wait for twelve hours before their flight left.

=> Only (a)  

I didn't realize who he has until later.

=> Only (a)  

The door could not be opened without using force.

=> Only (a)  

I won't agree until Tom's apologized.

=> Only (a)  

The only way you can become a good athlete is by training hard every day

=> Only (a)  

If the salary were high, the job would be worth doing.

=> Were (a)  

Would you visit me if I were sent to prison?

=> Were (a)  

I didn't see the signal, so I didn't stop.

=> Were (a)  

If I were rich, I could afford to buy an expensive car.

=> Were (a)  

If I were you, I would tell him the truth

=> Were (a)   .