1. When I was driving down the road, a cat appeared in front of my car. I immediately stopped the car. When I got out, I saw that it had run away.
2. He looked at the boy and immediately realized that he had seen him somewhere before.
3. A friend of mine has been collecting letters from the time she was in high school. Now she has gathered so many of them that she does not know where to keep them.
4. Here they are! We have been looking for you everywhere. Where have you been?
5. Yesterday, our class went to the museum. I did not go with them because I had already been there.