=>
1. How long have you studied English?
-> How long have/has S V3/ed? (bao lâu)
2. My father prefers living in the country to living in the city.
-> prefer Ving to Ving : thích làm gì hơn
3. Forty percent of the world's oxygen is produced by the Amazon Valley.
-> bị động HTĐ is/am/are V3/ed
4. Keiko and Tato told that they were going camping that weekend.
-> câu tường thuật -> lùi thì, HTTD -> QKTD
5. I asked Hoa if she went to the concert at Ben hanh theater.
-> câu tường thuật dạng Yes/No questions : asked sb if S V (lùi thì, HTĐ -> QKĐ)
