$\text{1. Where is Peter reading books at?}$

$\text{2. What are they doing in the park?}$

$\text{3. What musn't they do in the classroom?}$

$\text{4. How often do they stay up late?}$

$\text{5. What do many girls do at the weekend?}$

1. Peter is reading books in the bedroom. 

→ Where is Peter reading books at?

2. They are playing in the park.  

→ What are they doing in the park?

3. We mustn’t drink and eat in the classroom.

→ What mustn't we do in the classroom?

4. We sometimes stay up late on Saturday night.

→ How often do they stay up late?

5. Many girls do aerobics at the weekend.

→ What do many girls do at the weekend?