Яправильно написал на .i am a doctor and he is a teacher.

Да конечно правильно ))

Да, правильно.  Можно было сократить: I`m doctor and he`s a teacher.

It was snowing all day yesterday.     was itsnowing all day yesterday?  
it was not snowing all day?
They were doing their homework when I came to see them. Were they doing their homework when I came to see them?    They weren’t doing their homework when I came to see them.
They were cleaning this flat all morning. Were they cleaning this flat all morning?
They weren’t cleaning this flat all morning.
She burnt her hand when she was cooking dinner. When was she burnt her hand?
She burnt her hand when she weren’t cooking dinner.

1) I... home very early yesterday afternoon. c) came
2) While my friend I was watching the birds. c) was fishing
3) He said I...up the story myself. c) had made
4) My elder brother ... school 3 years ago.  b) finished
5) Before mother called us she ...the table.  c) had set 
1) When the bell rang the children ran into  the classroom and took their seats.
2) When I opened the door, the lesson had begun and the teacher was  explaining something to the class.
3) Before we took the boy to the theatre he had never seen a play.
4) By the time we arrived the party had finished.
5) What were you doing when I called you? - I was cooking.
6) When I got to the playground my friend had already left.
7) We had a good long holiday after we had done all the work.