II.
1. How many books has her mother written so far? (số lượng→ how many)
2. Why do you like doing volunteer work? (lí do→ why)
3. When did they provide evening class for street children? (thời gian→ when)
4. How can everyone keep the streets clean? (làm thế nào→ how)
5. What should we do to reduce trafic jams? (làm gì→ what)