Ответ:
1. Entering the room, he saw Anna where he had left her.
2. I noticed when I came in that someone had left the umbrella on the porch.
3. He did not read half a book, when he said that he did not like it.
4. When the guests left, she went into the living room and turned off the light.
5. She sat on the sofa and wondered why the letter from her father had not yet arrived.
6. The rain had stopped, but there was still a slight mist in the air. 7. I didn't know when he left.
8. He did not remember his name, nor did he remember ever meeting him before.
9. We were driving for two hours when we finally saw the lake.
10. It was some time before they realized he had nothing to say. 11. When he arrived home, he found out that his sister had just left.
12. When the expedition returned, they told what they had seen in the Arctic region.
13. She had finished packing by the time her sister knocked on the door.
14. It's been very cold the last few days, but it hasn't snowed.
15. When everyone had gone, she went to the phone and quickly dialled the number.
16. When my parents came back, I showed them what I had done. 17. Mom tried to calm me down after you left.
18. I was surprised at the progress she had made, considering how little time had passed since I had last seen her.
19. No sooner had he reached the door than he met his school friends.
20. He returned to Moscow, where he lived with his parents as a child.
21. When they finally parted, he returned to the room and went straight to the table.
22. It was much colder than she had expected.
23. I knew they'd met before the war.
24. When everyone had gone, I closed the door carefully.
25. When the dawn broke, the storm was still blowing, but the snow stopped.