преобразовать из этих предложений вопросы. И если нетрудно объясните как их составили. 1.They are cleaning the flat.
2.Tom is sad.
3.My sister and brother will help me.
4.She bought a new dress.
5.I trevel to visits his parents.

1. What are they doing?

2. Who is sad ?

3. will your sister and brother help you?

4. Did she buy new dress ?

5. Did you visit your parents?

нужно поменять подлежащее и сказуемое местами:

1. Are they cleaning the flat?

2. Is Tom sad?

3. Will my sister and brother help me?

4. Is she bought a new dress?

5. Am I trevel to visits his parents?

P.S. я не знаю точно, но вроде бы верно :)