Are Julie and Peter standing?
No, they arent. They are sitting

They are sitting at the table?
Yes they are.The are sitting at the table

Is Debbie smiling?
Yes she is.She is smilling

Are Julie and Peter listening music?
No they arent. They are reading book

The are watching TV?
No, they arent.They are speaking with each other (между собой)

Is Debbie carrying umbrella?
No, she isnt.She carrying book.

Are Julie wearing trousers?
No/Yes(я не вижу просто)
2 варианта : 
No , she isnt. She wearing a flat shoes.(плоская обувь,балетки типо)
Yes she is. She wearing trousers.

Are they drinking milk?
такой же случай не вижу)
2 варианта:
No they arent. They are drinking  tea/cacao
Yes they are. They are drinking milk