Một hộp kín có 4 đầu ra bên trong chứa các điện trở bằng nhau. Đo điện trở của các đầu ra ta đc kết quả như sau R12=R13=R23=R14 và R24=0. Xác định sơ đồ mạch điện trong hộp kín.

Có 3 điện trở R₁=3\(\Omega\); R₂=4\(\Omega\); R₃=6\(\Omega\) được mắc với nhau. Hãy chỉ ra có bao nhiêu cách mắc? Trong các cách đó cách nào có điện trở tương đương nhỏ nhất?

*Give the correct form of verbs

1-I've decided (stay) here over vacation

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2-We went for a walk when we finished(clean) up the kitchen

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3-I don't mind(wait) for you

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4-Did Helen agree(go) camping with you?

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5-The taxi wanted the passenger (pay) in cash

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6-The travel agent advised us(wait) until June

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7-Pat told us(not tell) her about that

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8-He came down to tea after(wash) his face

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9-I'd like (see) John tomorrow

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10-He needs(repair) this machine

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11-I stopped for a moment (speak) to him

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12-I'll consider(work) with him

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13-Would you mind (help) me with pushing this?

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14-She enjoy(go) (shop) with her friend

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15-I'm looking forward (hear) from you

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16-Should we(help) him?

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17-I suggest(go) to the countryside at weekend

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18-He kept(talk) about you last night

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19-He is fond of (read) picture books

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20-They have just (make) a new style of Jeans.

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21-She is very happy(see) him

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22-It started(rain) an hour ago. Has it stopped (rain) yet?

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23-Our teacher made me(answer) all the questions

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24-I hope(see) you again

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25-They refuse (go) out on a trip if it's too hot

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26-Let me(pay) for the meal. You paid last time.

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27-We began(talk) about next year's holiday two months ago

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28-Did you have any difficulty(get) a visa?

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29-Can you help me(get) the dinner ready?

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30-I really dislike (answer) the questions in front of the class

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31-She expects(pass) the next exam

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32-They offer(have) a cup of tea

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33-He threatened(kill) me

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34-They pretend(not know) the truth

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35-I can't help(laugh) at her

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36-She admitted(steal) my money

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37-She often practices(play) the piano in the morning

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38-She manages(pass) the exam

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39-She claims(see) a ghost

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40-I like Geogre but I think he tends(talk) too much.

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41-They desire(work) in a big factory

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42-I asked how (get) to the station

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43-Have you decided where(go) for your holiday?

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44-Remind me(call) Ann tomorrow

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45-He persuade me (attend) the course

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46-We are interested in(see) this film

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47-She is capable of (do) this work

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48-She has succeeded in (persuade) me

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49-I can't stand(work) with him

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50- I remember (see) her there before

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Bài 1:

Đặt cốc A đựng dung dịch HCl và cốc B đựng dung dịch H₂SO₄ loãng lên 2 đĩa cân sao cho cân ở vị trí cân bằng. Tiếp đến thực hiện các thí nghiệm sau đây:

- Cho 5,6 g Fe vào cốc đựng dung dịch HCl.

- Cho a gam Al vào cốc đựng dung dịch H₂SO₄.

Khi cả Fe và Al đều tan hoàn toàn thấy cân ở vị trí thăng bằng. Hãy tính a?

Bài 2. Cho 38,168 ml dung dịch H₂SO₄ 19,6% (d =1,31 g/ml) vào 208 gam dung dịch BaCl₂ 10%.

a. Viết PTPU xảy ra và tính khối lượng kết tủa tạo ra sau PU.

b.Tính nồng độ phần trăm của dung dịch thu được sau phản ứng khi đã loại bỏ hết kết tủa.

Bài 3. Dẫn khí CO dư qua ống đựng bột một oxit sắt (Fe_xO_y) ở nhiệt độ cao. Sau khi phản ứng kết thúcthu được 0,84 gam sắt và dẫn khí sinh ra vào nước vôi trong dư thì thu được 2 gam kết tủa. Xác định công thức phân tử của Fe_xO_y.

Chuyển sang câu bị động
1. He has not just cooked a meal for family.

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2. She is not studying her lessons now.

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3. I cannot do this test very well.

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4. Mr. John has not drawn twenty pictures for all his life.

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5. Manh and Nam are not drawing a picture now.

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6. He did not use to drive his car to work last year.

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7. I will not see the dentist to check my teeth next week.

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8. She does not take her umbrella in case it will rain.

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9. Hai does not water the flowers every morning.

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10. She cannot see a small object in the far distance.

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11. Long is not cutting the papers into different shapes.

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12. Weeds do not cover the riverbank.

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13. Smoke did not fill the room.

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14. They can make tea with boiled water.

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15. He is instructing all the workers of the plan at the moment.

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16. A boy has just taken some of my books away.

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17. They will hold the celebration before January.

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18. They have to repair their car.

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