Here are the suggested answers to fill in the blanks:

1. **ask** that question?
2. **should** go to bed early.
3. **been** stolen.
4. **think** hiking is easy.
5. **for** her.
6. **wonders**.
7. **built** 10 years ago.
8. **Pagoda** last week.
9. **going** to school by bike.
10. Jack is **interested** in History.

So, the complete sentences would read:

1. Did you **ask** that question?
2. We suggest that they **should** go to bed early.
3. Anna's bike has **been** stolen.
4. Some people **think** hiking is easy.
5. Do you see Mary? I'm looking **for** her.
6. We need to protect our natural **wonders**.
7. This house was **built** 10 years ago.
8. We visited Perfume **Pagoda** last week.
9. I suggest **going** to school by bike.
10. Jack is **interested** in History.