Молекулярная масса кислароду

поставьте вопросы к выделенным словам.. Выделенные  слова " "

1. The train leaves "at 9".
2. We "have supper" at 8 p.m.
3. Old ladies like to sit "by fire".
4. His grandparents live in Gomel.
5. He visits "his" grandparents very often.
6. "Her" brother made "three" mistakes in his test.
7. "He" worked at a plant "last year."
8. "They" will remember "this day" for ever.
9. "She has a headache", so she will not go to school.