Change these sentences into the active voice: (Chuyển các câu sau sang câu chủ động)
1. Oil is obtained from under the ocean by workers.
2. A big house is being built in this garden by the family.
3. The cart was drawn by horses.
4. They will be helped by that kind woman.
5. Grass is eaten by cows and buffaloes.
6. The lesson was explained by the teacher.
7. Grammar is taught by Mr. Brown.
8. A hole was being dug in the garden by him.
9. Coffee is being made by the maid.
10. The box will be moved away from the window by us.
11. This tree was plainted by my grandfather.
Giúp với 
Change these sentences into the active voice: (Chuyển các câu sau sang câu chủ động)
1. Oil is obtained from under the ocean by workers.
-> Workers obtain oil from under the ocean.
2. A big house is being built in this garden by the family.
-> The family are building a big house in this garden.
3. The cart was drawn by horses.
-> House drew the cart .
4. They will be helped by that kind woman.
-> That kind woman will help them.
5. Grass is eaten by cows and buffaloes.
-> Cows and buffaloes eat grass.
6. The lesson was explained by the teacher.
-> The teacher explained the lesson.
7. Grammar is taught by Mr. Brown.
-> Mr. Brown taught grammar.
8. A hole was being dug in the garden by him.
-> He was dugging a hole in the garden.
9. Coffee is being made by the maid.
-> The maid is making coffee.
10. The box will be moved away from the window by us.
-> We will move the box away from the window.
11. This tree was plainted by my grandfather.
-> My grandfather planted this tree.
