1. He was very sorry that he didn’t see Andrey on her trip to London.
–>He greatly regretted not seeing Andrey on her trip to London
2. It’s thought that the accident was caused by human error.
–>The accident is thought to have been caused by human error
3. “Will you be visiting the Taj Mahal when you go to India?” he asked Elizabeth.
–>He asked Elizabeth if she would be visiting the Taj Mahal when she went