"You've saved my life. I thank you from the_________of my heart."

A. centre               

B. bottom                      

C. Top                           

D. depths

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 36 to 42.

Successful students often do the followings while studying. First, they have an overview before reading. Next, they look for important information and pay greater attention to it (which often needs jumping forward or backward to process information). They also relate important points to one another. Also, they activate and use their prior knowledge. When they realize that their understanding is not good, they do not wait to change strategies. Last, they can monitor understanding and take action to correct or “fix up” mistakes in comprehension. 

Conversely, students with low academic achievement often demonstrate ineffective study skills. They tend to assume a passive role, in learning and rely on others (e.g., teachers, parents) to monitor their studying, for example, low-achieving students often do not monitor their understanding of content; they may not be aware of the purpose of studying; and they show little evidence of looking back, or employing “fix-up” strategies to fix understanding problems. Students who struggle with learning new information seem to be unaware that they must extent effort beyond simply reading the content to understand and remember it. Children with learning disabilities do not plan and judge the quality of their studying. Their studying may be disorganized. Students with learning problems face challenges with personal organization as well. They often have difficulty keeping track of materials and assignments, following directions, and completing work on time. Unlike good studiers who employ a variety of study skills in a flexible yet purposeful manner, low-achieving students use a restricted range of study skills. They cannot explain why good study strategies are important for learning; and they tend to use the same, often ineffective study approach for all learning tasks, ignoring task content, structure or difficulty.

In compared with low-achieving students, successful students use______.

A. aimless study techniques    

B. various study skills 

C. restricted strategies    

D. inflexible study ways

Mark the letter A, B, C, or D on you answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.
Mary loved her stuffed animal when she was young. She couldn’t sleep without it.

A. When Mary was young, she loved her stuffed animal so much that she couldn‟t sleep without it.

B. When Mary was young, she loved her stuffed animal so as not to sleep without it.

C. When Mary was young, she loved her stuffed animal though she couldn‟t sleep without it.

D. As Mary couldn‟t sleep without her stuffed animal when Mary was young, she loved it.

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 43 to 50.

        An air pollutant is defined as a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals, vegetation, or materials adversely. Air pollution requires a very flexible definition that permits continuous changes. When the first air pollution laws were established in England in the fourteenth century, air pollutants were limited to compounds that could be seen or smelled - a far cry from the extensive list of harmful substances known today. As technology has developed and knowledge of the health aspects of various chemicals has increased, the list of air pollutants has lengthened. In the future, even water vapor might be considered an air pollutant under certain conditions.

        Many of more important air pollutants, such as sulfur oxides, carbon monoxides and nitrogen oxides are found in nature. As the Earth developed, the concentration of these pollutants was altered by various chemical reactions; they became components in biogeochemical cycles. These serve as an air purification scheme by allowing the compounds to move from the air to the water or soil. On a global basis, nature's output of these compounds dwarfs that resulting from human activities.

        However, human production usually occurs in a localized area, such as a city. In such a region, human output may be dominant and may temporarily overload the natural purification scheme of the cycles. The result is an concentration of noxious chemicals in the air. The concentrations at which the adverse effects appear will be greater than the concentrations that the pollutants would have in the absence of human activities. The actual concentration need not be large for a substance to be a pollutant; in fact, the numerical value tells us little until we know how much of an increase this represents over the concentration that would occur naturally in the area. For example, sulfur dioxide has detectable health effects at 0. 08 parts per million (ppm), which is about 400 times its natural level. Carbon monoxide, however has a natural level of 0. 1 ppm and is not usually a pollutant until its level reaches about 15 ppm.

For which of the following reasons can natural pollutants play an important role in controlling air pollution?

A. They're less harmful to living beings than other pollutants. 

B. They function as part of a purification process.

C.They occur in greater quantities than other pollutants.

D. They have existed since the Earth developed.

Tơ nitron (tơ olon) có thành phần hóa học gồm các nguyên tố là

A. C, H, N

B. C, H, N, O

C. C, H

D. C, H, Cl