@ Object or subject? What or who?

English learners  have sometimes doubts when asking questions about who or what has done something when they haven't paid attention to the subject or object of the sentence said by the speaker: 

" - He asked Peter about the burglary...
  - Sorry, who did he ask? 

" - They are building a castle in the sand...
  - Sorry, what are they building?


Now try to ask for the underlined words... 

1. Jane opened the door.
2. She usually stays at home because she hates travelling
3. They greet their teacher.
4. The flower pot fell on the floor. 
5. He flew to Manchester.
6. She bought three bottles of wine.     
7. Joe helped me in the garden.
8. They play tennis twice a week
9. The king sent me a letter
10. We usually take the elevator 

Solutions...........................................

Who opened the door?

Who usually stays at home?

Who greet their teacher?

What fell on the floor?

Who flew to Manchester?

What did she buy?

Who did he help?

What do they play twice a week?

What did the king send you?

What do you usually use?