Câu 1: Bạn Thiện muốn đo công suất của 1 quạt điện. Tuy nhiên, trong nhà bạn chỉ có các loại đồng hồ : Ampe kế, vôn kế, ôm kế mà mãi không có Oát kế nên mãi bạn không thực hiện được. Nếu là Thiện, em có làm được không ? Cho biết phương án của mình.
Câu 2: Trên vỏ hộp của 1 bóng đèn sợi đốt có ghi : 100W-220V. Làm thế nào để xác định chính xác điện trở của bóng đèn mà không dùng bất kì loại đồng hồ đo nào ? Trình bày phương án cụ thể
Cho ∆ABC nhọn, AC > AB, đường cao AN
A. Cho AN = 16cm, AB = 20cm. Giải tam giác vuông ANB ( góc làm tròn đến độ)
B. Gọi K và I lần lượt là hình chiếu của N lên AB và AC. Chứng minh : AI.AC= AK.AB. Từ đó tính số đo góc AIK
C. Chứng minh rằng : 2 < ( sinBAC)2(sinABC)2+(sinACB)2<3
Từ một đỉnh của một ngọn đèn biển cao 50m so với mặt nước biển, bạn Mai thấy một hòn đảo duwos góc 30 độ so với đường nằm ngang chân đèn. Bạn Mai dự định khám phá hòn đảo bằng một chiếc tàu và đi ra hòn đảo với quãng đường ngắn nhất, biết rằng trên con tàu còn 3,2lít dầ, cứ đi 10m thì tàu đó hao tốn hết 0,4 lít dầu. Hỏi bạn Mai có thể đi ra hòn đảo với số lượng dầu như trên hay không ? Vì sao ?
Change these sentences into the passive voice :
26. Will you invite her to your birthday party ?
27. The principal will hold an English speaking contest in Quang Trung school next month.
28. They have shown more than 50 films in Ha Noi since June.
29. Many people in the world speak English.
30. My Dad will prepare my bike tomorrow.
31. Mr. Bell invented the telephone in 1876.
32. Students should do the homework at home.
33. We have built a new road in the village.
34. Lan has learnt English for 3 years.
35. They sent a lot of flowers to her on her birthday.
36. We mustn't wear jeans at work.
37. We can't make tea with cold water.
38. The woman is making a cake for her children.
39. My son hasn't finished his homework.
Change these sentences into the passive voice :
11. Linda types the reports in this coffe.
12. They don't paint this gate every year.
13. She doesn't iron her clothes every morning.
14. The mechanic checks the car engines every week.
15. The milkman brings bottles of milk to houses.
16. Many people speak English as a second language.
17. People speak French and English in Canada.
18. Do they speak French and English in Canada?
19. How do people learn languages ?
20. Does your country export rice to Britain ?
21. The postman will deliver the mail tomorrow.
22. We haven't seen Mr.Black since we left school.
23. The workers will build many new houses im this area next year.
24. The committe won't change the plan of recycling.
25. John will collect me at the airport.
Change these sentences into the passive voice :
1. My mother cleans the kitchen every day.
2. They deliver our papers every morning.
3. They sell English books in that shop.
4. My sister washes our clothes every day.
5. They send the goods to Vung Tau by coach.
6. Our teacher corrects our homework every day.
7. The children usually eat vegetables and fruits.
8. My father cuts the grass in the garden every weekend.
9. People build new houses in this city every year.
10. People grow rice in these fields.
Read the passage carefully. Then decide whether each is True or False
- People pollute the environment by throwing litter or garbage all over the places every day. They also dump empty bottles or cans into the rivers, lakes and seas, making the water unclean. They also cut a lot of trees to get wood pulp for making paper. To protect the environment , everyone should classify and put the garbage in a certain bag for making compost and they should recycle waste paper to avoid cutting a lot of trees. We can protect our environment by doing like that. We also should plant more and more green trees because trees help to hold the soil, prevent us from floods and give us fresh air and shade in summer.
True or False ????
1. One of the factors leading to the water pollution is bottles and cans dumped into the rivers.
2. We don't need to clarify garbage because It doesn't help protect the environment.
3. In oder to prodect our environment, we have to plant more trees.
4. Trees should not be cut down so as to prevent us from floods.
Questions :
5. We should NOT......... so as to protect environment.
a. Classify and put the garbage in a bag for making compost.
b. Cut lots of trees to get wood pulp instead of recycling waste paper.
c. Plant more green trees.
d. All the correct.
6. What does the word " Classify " in the passage mean ?
a. Arrange things in groups according to their features.
b. Throw things in different directions.
c. Bring things together.
d. Reduce something