Tại sao chỉ từ 20 loại axit amin mà một tế bào có thể tổng hợp được rất nhiều loại protein ?

Exercise 1:Rewrite following sentences so that the meaning stay the same.

1.”If I were you,I wouldn’t buy this car”

àHe advised..............................................................................................

2.”Shall I carry your suicase,Lan?”said Nam.

àNam offered............................................................................................

3.”Yes,all right,I’ll share the food with you,Dave.”

àAnn agreed......................................................................................

4.”Sue,can you remember to buy some bread?”

àPaul reminded..........................................................................................

5.”Don’t touch anything in this room”,the man said to the children.

àThe man ordered.......................................................................................

6.”I must go home to make the dinner”,said Mary.

àMary...........................................................................................

7.”Are you going to Ho Chi Minh City next week?”Tom asked me.

àTom asked.................................................................................................

8.”Have you finished your homework?”Mom asked.

àMom asked if.............................................................................................

9.She said to me:”I can’t do it by myself”

àShe told me that........................................................................................

10.”Does your brother live in London,Nam?”Lan asked.

àLan wanted to know if.............................................................................

11.”Don’t repeat this mistake again.”his father warned him.

àHis father warned him.................................................................................

12.”Give me a smile,”The photographer said to me.

àThe...........................................................................................................

13.”Don’t leave these book on the table” ,the librarian said to the students

àThe librarian told the students....................................................................

14.”Have you travelled abroad much?”he asked me.

àHe.............................................................................................................

15.”Who has written this note?” the boss asked the secretary.

àThe boss asked...........................................................................................

16.”I have just received a postcard from my sister,”my friend said to me.

àMy friend told me.......................................................................................

17.”This story happened long ago”he said.

He said......................................................................................................

Exercise 2
1 "Don't repeat this mistake again!" the instructor warned the sports¬man.

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2 "Leave your address with the secretary," the assistant said to me.

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3 "Phone to me for an answer tomorrow” the manager said to the client.

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4 "Don't be so silly," the father said to the kid.

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5 "Give a smile," the photographer said to me.

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6 "Please, help me to make a decision," Ann asked her friend.

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7 "Don't leave these books on the table, put them back on the shelf," the librarian said to the student.

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8 "Be a good girl and sit quietly for five minutes," the nurse said to the child.

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9 "Leave your things here," my companion advised me.

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10 "Don't discuss this question now," said the chairman to the participants.

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Exercise 3
1 "Will it be safe to stay in the mountains for the night if the weather doesn't change for the better?" we asked the guide.

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2 The porter said to me, "I'll wake you up, when the train arrives in Leeds."

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3 My wife said to me: "While you are away, I'll do the packing."

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4 "Don't leave until I phone you," he asked me.

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5 "After he leaves hospital, they'll take him to the South," the doctor said.

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6 "They'll wait for the fisherman to return until it gets dark," the local man explained to me.

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7 As soon as I hear from him, I'll let you know," my neighbour said to me.

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8 I’ll live in town till my husband returns from the expedition and when he returns, we'll go to the seaside together," she said.

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9 The mother said to her son, ."Sit still, please."

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10 John said to his friend, "Come and spend a week with us."

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Exercise 4
1 "Have you travelled abroad much?" he asked me.

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2 "Who has written this note?" the boss asked the secretary.

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3 "I've just received a postcard from my sister," my friend said to me.

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4 "The students also took part in arranging the conference," the chair¬man said.

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5 "Have you been here long?" the stranger asked me.

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6 "Did you really see this happen with your own eyes?" the policeman asked the boy.

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7 "I hope they will have taken a decision by the end of the meeting," she remarked.

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8 "Did you watch the detective film on TV yesterday?" he asked her.

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9 "This story happened long ago," he said, "and few people remember anything about it."

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10 "I haven't read so interesting a book since I don't remember when," she said.

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Exercise 5
1 Tom said to the girl: "When did you have this picture taken?"

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2 "Shall we go somewhere for a cup of coffee after class?" Tom said.

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3 John said to Mary, "Why don't you wear your hair a little longer."

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4 "Would you like another cup of tea?" the landlady said to the guest.

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5 My sister said to me, "What about going to see Aunt Mary on Sunday?"

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6 She asked me, "Have you ever seen a flying saucer?"

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7 James said: "Do you want me to type this letter for you?"

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8 Alfred said to John, "I didn't use your cassette player! Someone else did, not me."

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9 Father said, "I was the superintendent while this school was being built."

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10 The woman said, "If I had a gas stove, it would save me a lot of time."

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Exercise 6
1 Jane said to Bill, “When do you expect to finish your assignment?"

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2 The man said to the boy: "Can you show me the way to the bank?"

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3 Fred asked the postman: "Are there any letters for me today?"

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4 Henry said to the librarian, "How many books can I borrow at a time?"

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5 John asked his friend, "How did you manage to know my phone number?"

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6 “These old buildings might have already disappeared by the time I am back next year?" he said

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7 The boys said to the old woman: "What can we do to help you?"

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8 The guests said to the doorman: "Where should we leave our coats?"

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9 Tom asked his brother: "Why did you advise them to go sight-seeing on foot?"

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10 I asked the children: "Who took away the magazines from my desk?"

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Exercise 7
1 Rose said, "I was just leaving the office when I came face to face with a stranger."

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2 Ann asked her brother, "Do you expect to be admitted to the univer¬sity?"

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3 Richard asked Jane, "What are you planning to do tomorrow?"

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4 She asked her boy friend "Is it true that your father fought in the last war?"

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5 Jane said to me, "Where have you been all this time?"

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6 Mary said to her husband, "Did you see my handbag anywhere?"

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7 The inspector said to the woman, "What were you doing at 7 o'clock yesterday evening?"

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8 The passenger said to the taxi-driver: "Hurry up!" and he added "I must be at the station on time."

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9 Tom said to himself: "Why I haven't thought of this before?"

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10 Father said: "The taxi is coming now. Is everyone ready?"

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Exercise 8
1 Helen said, "I think I'll have to find a better job. I can't make both ends meet."

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2 He said to her "Why are you so late? I've been waiting for half an hour already."

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3 She said to him: "Don't let them down. I'll be very embarrassed if you go back on your words."

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4 She said to her husband: "You'd better not drink top much. You may lose control of the car and have a bad accident."

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5 The boy said to his mother: "When shall we have lunch? I'm very hungry."

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6 He said, "I don't understand why she has refused to join us on the trip."

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7 She said to him, "I'm glad you've come. Sit down, please."

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8 Mr Brown said to his wife, "I don't feel like going out this evening.”
Let's ask the Browns to come over for a chat."

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9 “It's raining too hard to go out. We'd better stay home tonight and watch TV instead." John said.

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10 "Could you ring up the station and find out when the train comes in?" said Tom to me.

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Exercise 9
1 "Be careful. Don't go too near the edge of the cliff," she said to the boys.

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2 "Please, please come to help me with the assignment," my friend said to me.

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3 "I wouldn't buy that sort of raincoat if I were you," my friend said to me.

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4 "Would you mind moving your bicycle?" said the janitor. "It's in the way."

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5 "Could I take out another book, please," I said to the librarian.

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6 "Remember to leave the window open when you're using the gas stove," my mother said to me.

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7 "Wear your school badge or they won't let you into the classroom." my teacher said to me.

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8 "Would you like to come over to my house for a slide show?" my friend said to me.

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9 "Show me your driver's licence, will you?" the policeman said to the drunken driver. .....................................................................................................................................................................................................................................
10 "Do come again next weekend," the host said to the visitor.

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Vị trí địa lý của tỉnh Hà Giang và lãnh thổ

tài nguyên sinh vật tỉnh Hà Giang

3 câu văn trên đây đã miêu tả được công việc vô cùng khó khăn gian khổ của ba cô gái thanh niên xung phong trong bài Những Ngôi Sao Xa Xôi của Lê Minh Khuê công việc của ba cô gái đã được Hiện ra trước mắt người đọc một cách chân thực một công việc gian lao vất vả phá bom không ngần ngại ,thể hiện rõ sự tự nguyện thái độ với công việc của ba cô gái Công việc ấy ấy đòi hỏi ở họ phải bình tĩnh, dũng cảm, khôn ngoan, nhạy cảm và kháo léo, đòi hỏi kinh nghiệm và sẵn sàng hy sinh, không quản khó khăn gian khổ bởi chẳng có ai biết được quả bom câm lặng có khi đang ấm nóng dần lên, nằm chềnh ềnh ra đó và có thể nổ bất cứ lúc nào. họ là những người có trách nhiệm tự giác rất cao, quyết tâm hoàn thành mọi nhiệm vụ đư­ợc phân công bởi công việc của họ không hề đơn giản. Đố là những phẩm chất cao đẹp, bình dị, hồn nhiên của ba cô gái thanh niên xung phong Như vậy vẻ đẹp trong cuộc sống chiến đấu của tổ trinh sát mặt đường: Nho, Phương Định, chị Thao chính là vẻ đẹp của thế hệ trẻ thanh niên xung phong trong thời kỳ kháng chiến chống Mỹ mà Lê Minh Khuê đã tả lại rất thành công,

a) do dv=10500N/m3 và dn=10000N/m3 nên dv>dn

=>vật chìm xuống

b)thể tích của vật là:

Vv=P/dv=>Vv=6/10500=1/1750(m3)

lực đẩy ac-simet là

=>FA=dn*Vc=10000*(1/1750)=5.714(N)