Ответ:
4. It WAS nine o’clock and we HAD COME to her room two hours before, as we often DID on those winter evenings.
15. Talking to him WAS very easy; just like talking to someone you HAD KNOWN all your life.
16. When he CAME back to his seat his manner HAD CHANGED. He WAS gentle and kindly.
17. George MADE no answer, and we FOUND that he HAD BEEN asleep for some time.