1 I didn’t recognize Helen, because she had cut her hair very short.
2 No one understood how the cat had got into the car.
3 Joe didn’t play in the game on Saturday because he had hurt his arm.
4 When I had looked in all my pockets for my keys, I started to get worried.
5 Mary had never travelled by train before she went to Europe.
6 I arrived at the shop at six, but it had already closed.