Each of the following sentences has ONE grammatical mistake. Underline the mistakes and write the correct sentences.
1. In my opinion, I think students should not date as it can affect their studies.2. Do you know which book should we buy for the new course?3. She does not like wearing a dress. Neither I do.4. He is not possible to win in the singing contest as he has a sore throat.5. I and my friends will travel to Japan next week.6. Oliver cannot afford buying that evening gown for attending the party.7. If I were the president, I will reform the unfair system.8. This stone is more smooth than that one.9. The department store is nearby the police station.10. Not only David but also Amy like to stay up late at night watching TV.11. Only in this way we can beat the deadline for the project.12. She can speak very well Spanish as she has studied in Spain for two years.