1. It's not common for there to be so much rain in March
-> Seldom is there so much rain in March
2. You won't allowed in until your indentify has been checked
-> Only when your identity has been checked will you be admitted.
3. Just after the play started there was a power failture
-> Hardly had the play started when there was a power failure
4. The Prime Minister has hardly ever made a speech as inept as this
-> Rarely has the Prime Minister made so inept a speech.
5. We had only just arived home when the police called
-> Scarcely had we arived home when the police called.