Join the two sentences using when and the Past Perfect in one of the parts of the sentence.
1. Pierre arrived at the airport. The plane left.
2. I switched the TV on. The programme started.
3. The thief ran away. He snatched all the money from the cashier.
4. I got to the concert hall. The show began.
1. The plane had left when Pierre arrived at the airport.
2. The programme had started when I switched the TV on.
3. The thief had run away when he snatched all the money from the cashier.
4. The show had begun when I got to the concert hall.