chuyen sang cau (-),(?)
1.He sent letter to his friends→ He didn't send letter to his friends
...............................................Did he send letter to his friends?
2.My brother spent his summer holiday on the farm→ My brother didn't spend his holiday on the farm
..............Did your brother spend his holiday on the farm
3.The children wash their hands before meals→ The children didn't wash their hands before meals
...........Did the children wash their hands before meals
1.He sent letter to his friends
=> (-): He didn't send letter to his friends
(?): Did he send letter to his frrends?
2.My brother spent his summer holiday on the farm
=> (-): My brother didn't spend his summer holiday on the farm
(?): Did your brother spend his summer holiday on the farm?
3.The children wash their hands before meals
=> (-): The children don't wash their hands before meals
(?): Do the children wash their hands before meals?