1. Tom was writing 2 poems.

2. Workers were digging s lsrge hole in the ground

3. Cows were eating grass on the meadow.

4. Her father was plating diffrent kinds of flowers in the garden.

5. They were continually asking questions.

6. The boy screamed while the dentist was pulling out one of his teeth

7. When I arrived, someone was cleaning the room.

8. Tom was doing his homework at 7.00 yesterday.

9. When I came home from school, my mother was cooking dinner.

Chuyển sang câu bị động:

1. People are discussing some urgent issues.

2. My teacher is showing me how to write an academic piece of writing.

3. They are building several new schools in town.

4. People are talking about him everywhere.

5. They are growing trees around their school to make a fence.

6. The secretary is counting mooney.

7. I am translating an aricle from English into Vietnamese.

8. Someone is following us.

9. Countries are finding a way to solve the problem.

10. He is prepating everything for the presidential election.

11. She is running her owwn company.

12. The Prime Minister is making a speech at the moment.

Chuyển sang câu bị động:

1. He wrote the letters.

2. Did these engineers build the brige?

3. She asked me to be at her house at six o'clock.

4. They painted the house red.

5. Did the Queen or the Prime Minister open the Festival?

6. Who hit him?

7. They gave up te search after 3 hours.

8. The fire destroyed many valuable paintings.

9. Did she buy a camera yesterday?

10. Her teacher promised her a prize.

11. The elephants fascinated the children most.

12. They kept the performing animals in iron cages.

13. The police didn't give him a driving license.

14. They painted the clown's face white and red.

15. Who wrote it?

16. His grandmother brought him up in Hanoi.

Cho hai lò xo có cùng chiều da tự nhiên và độ cứng lần lượt là k₁ = 40 N/m, k₂ = 60 N/m. Đầu trên của hai lò xo cùng gắn vào một điểm cố định, đầu dưới của hai lò xo cùng gắn vào quả nặng khối lượng 180g. Biết gia tốc rơi tự do là 10 m/s². Tính độ biến dạng của chúng khi quả nặng nằm cân bằng.

\(3\sqrt{2+x}-6\sqrt{2-x}+4\sqrt{4-x^2}=10-3x\)

\(x^2-7x+4=2\sqrt{5x-4}\)