Chất nào sau đây trùng hợp tạo thành PVC

A. CH₂=CHCl

B. CH₂=CH₂

C. CHCl=CHCl

D. CH≡CH

câu nào đúng zậy

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 38 to 42.

(1) Colors are one of the most exciting experiences in life. I love them, and they are just as important to me as emotions are. Have you ever wondered how the two are so intimately related?

(2) Color directly affects your emotions. Color both reflects the current state of your emotions, and is something that you can use to improve or change your emotions. The color that you choose to wear either reflects your current state of being, or reflects the color or emotion that you need.

(3) The colors that you wear affect you much more than they affect the people around you. Of course they also affect anyone who comes in contract with you, but you are the one saturated with the color all day! I even choose items around me based on their color. In the morning, I choose my clothes based on the color or emotion that I need for the day. So you can consciously use color to control the emotions that you are exposed to, which can help you to feel better.

(4) Color, sound, and emotions are all vibrations. Emotions are literally energy in motion; they are meant to move and flow. This is the reason that real feelings are the fastest way to get your energy in motion. Also, flowing energy is exactly what creates healthy cells in your body. So, the fastest want to be healthy is to be open to your real feelings. Alternately, the fastest way to create disease is to inhibit your emotions. 

What is the main idea of the passage?

A. Colors are one of the most exciting.

B. Colors can help you become healthy. 

C. Emotions and colors are closely related to each other. 

D. Colorful clothes can change your mood.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 33 to 37. Fill in the appropriate word in question 37

Some years ago, my daughter was studying English at a university on the south coast. One evening she phoned to tell me that what she really wanted to do was looking (33) _____ the world, so she was looking into the possibility of working in another country. She had seen several (34) _____ in the newspaper for student teachers of English abroad, and she was interested in one in Italy, which she was desperate to visit. She decided that this would be a good way to achieve her ambition, so she was writing to apply for the job. The reply took a long time to arrive, but eventually she received a letter asking if she would go for an interview in London the following week. She was so excited that she immediately got in touch with the school owner and agreed to attend the interview. She was determined that nothing would prevent her (35) _____ doing what she had set out to do. A few days before the interview she had a very strange dream in which she gave birth to a beautiful baby. She was a little nervous and (36) _____ about the dream and phoned to ask me what I thought it might mean. As I knew something about dreams, I was able to assure her that it only symbolized her (37) _____ to do well in the interview. 

A. desire

B. want

C. demand

D. request

Một trong những hướng vận chuyển các chất hữu cơ của dòng mạch rây là:

A. Từ lá đến rễ.

B. Từ cành đến lá.

C. Từ rễ đến thân.

D. Từ thân đến lá.

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 36 to 42.

A rather surprising geographical feature of Antarctica is that a huge freshwater, one of the world's largest and deepest, lies hidden there under four kilometers of ice. Now known as Lake Vostok, this huge body of water is located under the ice block that comprises Antarctica. The lake is able to exist in its unfrozen state beneath this block of ice because its waters are warned by geothermal heat from the earth's core. This thick glacier above Lake Vostok actually insulates it from frigid temperatures (the lowest ever recorded on Earth) on the surface.

The lake was first discovered in the 1970s while a research team was conducting an aerial survey of the area. Radio waves from the survey equipment penetrated the ice and revealed a body of water of indeterminate size. It was not until much more recently that data collected by satellite made scientists aware of the tremendous size of the lake; satellite-borne radar detected an extremely flat region where the ice remains level because it is floating on the water of the lake.

The discovery of such a huge fresh water lake trapped under Antarctica is of interest to the scientific community because of the potential that the lake contains ancient microbes that have survived for thousands upon thousands of years, unaffected by factors such as nuclear fallout and elevated ultraviolet light that have affected organisms in more exposed areas. The downside of the discovery, however, lies in the difficulty of conducting research on the lake in such a harsh climate and in the problems associated with obtaining uncontaminated samples from the lake without actually exposing the lake to contamination. Scientists are looking for possible ways to accomplish this.

Question 42: The paragraph following the passage most probably discusses _________.

A. further discoveries on the surface of Antarctica

B. problems with satellite-borne radar equipment

C. ways to study Lake Vostok without contaminating it

D. the harsh climate of Antarctica

Dạng carbon nào là chất đầu vào chủ yếu cho các hệ sinh thái trên cạn?

A. Carbonic

B. Carbon monoxide

C. HCO₃^-

D. Chất hữu cơ

Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.
On the second thought, I believe I will go with you to the theater.

A. On reflection             

B. For this time only

C. After discussing with my life        

D. For the second time

Tất cả các câu sau đúng về điều hòa quần thể, ngoại trừ:

A.  Phương trình tăng trưởng quần thể trong môi trường bị giới hạn phản ánh ảnh hưởng của các nhân tố phụ thuộc mật độ tới sự cân bằng quần thể quanh sức chứa môi trường.

B.  Nhân  tố không phụ thuộc mật độ sẽ ảnh hưởng lớn tới quần thể khi mật độ tăng.

C.  Mật  độ quần thể tăng có thể làm thay đổi sinh lý của cá thể và ức chế sinh sản.

D. Quần thể thường biến động số lượng theo chu kì là sự đáp lại của quần thể với nhân tố phụ thuộc mật độ.