Read the following passage and mark the letter A, B, C, or D to indicate the best option for each of the blanks.

Why do people like to chew gum? Some people say they like the taste. (46) ________say they can think better if they chew gum. Some people chew it when they have some boring work to do. Others chew gum when they are nervous.

Gum is a mixture of things. For many years gum companies made gum from chicle. Chicle is a natural gum from a tree in Mexico and Central America. Now companies use plastic and rubber made from petroleum (47) ________of chicle.

Gum must be soft so that you can chew it. A softener keeps it soft. The gum company makes the softener from vegetable oil. A sweetener makes the gum sweet. The sweetener is usually sugar. Then the company (48) ________the flavor.

Thomas Adams made the first gum from chicle in 1836. However, chewing gum was not new. The Greeks chewed gum from a tree (49) ________2,000 years ago. Mayan Indians in Mexico chewed chicle. Indians in the Northeastern United States taught Europeans to chew gum from a tree there.

People first made bubble gum in 1928. Children like to (50) ________bubble with bubble gum. Some university students do too.

Điền vào câu 49

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions

We cut down many forests. The Earth becomes hot

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions

He is very intelligent. He can solve all the problems in no time

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions

Had she read the reference books, she would have been able to finish the test

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions

“I will pay back the money, Gloria.” Said Ivan

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions

It started to rain at 2 o’clock and it is still raining

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions

I don’t mind waiting for other ten minutes, but will you please keep me company? 

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions

Caroline has worn her new yellow dress only once since she buys it

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions

The police told us to refrain from touching the furniture in case they would need to look for fingerprints

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 35 to 42 

     Many ants forage across the countryside in large numbers and undertake mass migrations; these activities proceed because one ant lays a trail on the ground for the others to follow. As a worker ant returns home after finding a source of food, it marks the route by intermittently touching its stinger to the ground and depositing a tiny amount of trail pheromone – a mixture of chemicals that delivers diverse messages as the context changes. These trails incorporate no directional information and may be followed by other ants in either direction. 

     Unlike some other messages, such as the one arising from a dead ant, a food trail has to be kept secret from members of other species. It is not surprising then that ant species use a wide variety of compounds as trail pheromones. Ants can be extremely sensitive to these signals. Investigators working with the trail pheromone of the leafcutter ant Atta Texana calculated that one milligram of this substance would suffice to lead a column of ants three times around Earth. 

          The vapor of the evaporating pheromone over the trail guides an ant along the way, and the ant detects this signal with receptors in its antennae. A trail pheromone will evaporate to furnish the highest concentration of vapor right over the trail, in what is called a vapor space.  In following the trail, the ant moves to the right and left, oscillating from side to side across the line of the trail itself, bringing first one and then the other antenna into the vapor space. As the ant moves to the right, its left antenna arrives in the vapor space. The signal it receives causes it to swing to the left, and the ant then pursues this new course until its right antenna reaches the vapor space. It then swings back to the right, and so weaves back and forth down the trail

According to the passage, the highest amount of pheromone vapor is found _____ 

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 35 to 42 

     Many ants forage across the countryside in large numbers and undertake mass migrations; these activities proceed because one ant lays a trail on the ground for the others to follow. As a worker ant returns home after finding a source of food, it marks the route by intermittently touching its stinger to the ground and depositing a tiny amount of trail pheromone – a mixture of chemicals that delivers diverse messages as the context changes. These trails incorporate no directional information and may be followed by other ants in either direction. 

     Unlike some other messages, such as the one arising from a dead ant, a food trail has to be kept secret from members of other species. It is not surprising then that ant species use a wide variety of compounds as trail pheromones. Ants can be extremely sensitive to these signals. Investigators working with the trail pheromone of the leafcutter ant Atta Texana calculated that one milligram of this substance would suffice to lead a column of ants three times around Earth. 

          The vapor of the evaporating pheromone over the trail guides an ant along the way, and the ant detects this signal with receptors in its antennae. A trail pheromone will evaporate to furnish the highest concentration of vapor right over the trail, in what is called a vapor space.  In following the trail, the ant moves to the right and left, oscillating from side to side across the line of the trail itself, bringing first one and then the other antenna into the vapor space. As the ant moves to the right, its left antenna arrives in the vapor space. The signal it receives causes it to swing to the left, and the ant then pursues this new course until its right antenna reaches the vapor space. It then swings back to the right, and so weaves back and forth down the trail

The word “oscillating” in line 17 is closest in meaning to