1. Was the weather fine yesterday?
     When was the weather fine?
     Was the weater fine yesterday or the day before yesterday?
   The weather was fine yesterday, wasn't it?
     What was fine yesterday?
2. Are we doing the exercise?
     What are we doing?
     Are we doing the exercise or the test?
     Who is doing the exercise?
     We are doing the exercise, aren't we?
3. Do they walk along the street every day?
   How often do they walk along the street?
Do they walk along the street or along the road every day?
They walk along the street every day, don't they?
Who walks along the street every day?
4.Did they translate a difficult text yesterday?
   When did they translate a difficult text?
  Did they translate a difficult text or an easy text yesterday?
they translated a difficult text yesterday, didn't they?
who translated a difficult text yesterday?
5. Has My friend helped me to solve a problem yet?
My friend has  helped me to solve a problem, hasn't he?
Why has My friend helped me to solve the problem?
Has My friend or my teacher helped me to solve a problem?
Who has helped me to solve the problem?