Trên mặt nước có hai nguồn phát sóng S 1 , S 2  dao động theo phương thẳng đứng với phương trình giống hệt nhau là u   =   5 cos 6 π t cm. Tốc độ truyền sóng trên mặt nước bằng 9 cm/s. Điểm M trên mặt nước cách các nguồn  S 1 , S 2 các khoảng cách tương ứng là 17 cm và 26 cm. Độ lệch pha của hai sóng thành phần tại M bằng

A. π

B. 0

C. π/2

D. π/3

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

The Industrial Revolution in Britain was built on the use of machines in factories. Since the 1950s, Britain's (34) _______ industries have replaced machine operators with computers, and this (35) ________ has led to a decline in the number of (36) ________ in many factories. Goods are bought and used much more than ever before but a lot of these goods are imported. By the beginning of the 20th century, other industrial countries like the USA were (37) ________ with Britain's exports, and countries in the Far East have been able to provide cheaper (38) _________since the 1970s. Areas located with heavy industries are suffering high unemployment. During the last 30 years, there has been a constant rise in smaller industries (39) ________ as "light industries". These ones use electricity and are not (40) _________ on raw materials such as coal so they are "footloose", i.e. they can be located anywhere. They produce such things as washing machines or spare (41) ________. Some of these industries produce nothing at all, but provide services like distribution. The consumer boom of the 1980s and the increased leisure time of most Britons have led to rapid (42) ________ in service industries like banking, tourism, retailing and information processing, and in industries which distribute, maintain, and repair (43) _________ consumer goods.

Điền vào câu 38

A. things

B. products

C. produce

D. imports

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 24 to 33.

An endangered species is a species (24)_______ population is (25) _______small that it is in danger of becoming extinct. Many countries have laws offering special protection to these species; (26) _______, forbidding hunting (27)_______ banning their sales. Only a few of the many truly endangered species actually make it to the lists and obtain legal protection. Many more species become extinct, or potentially become extinct, without gaining public notice.

Many of these laws are (28) _______. Typical areas of controversy include: criteria for placing a species on the endangered species list, and criteria for removing a species (29)_______ the list once its population has recovered.

A listing as an endangered species can backfire, as it (30)_______ a species more valuable and more desirable for collectors and poachers.

The conservation status of a species is an indicator of the (31)_______of that endangered species continuing to survive. Many factors are taken (32)_______ account when assessing the conservation status of a species: not simply the number remaining, but the overall increase or decrease in the population over time, breeding success rates, known threats, and so on.

The best-known worldwide conservation status listing is the World Conservation Union Red List. (33)_______ , many more specialized lists exist

Điền vào ô số 28

A. controversy 

B. controversially 

C. controversialist 

D. controversial

Read the following text and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions

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 phrase “the one” in paragraph 2 refers to a single

A. message

B. food trail 

C. dead ant  

D. species

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

She is intelligent. She can sing very well.

A. Intelligent as she is, she also can sing very well

B. Not only is she intelligent but she can also sing very well

C. She is intelligent, so she can sing very well

D. Not only intelligent is she but she also can sing very well

With job vacancies available all year round offering high salaries, Vietnam has been ranked the second best place in the world to teach English by TEFL Exchange, a community for teachers of English (1)______ a foreign language.

The site (2)______ that a foreign English teacher can earn between 1,200-2,200 USD a month in Vietnam, where the average annual income in 2016 was just 2,200 USD. They can (3)______ a job any time of year and the best places to do so are the country’s three largest cities: Hanoi, Ho Chi Minh City and Da Nang. Candidates only need to hold a bachelor’s (4)______ and a TEFL (Teaching English as a Foreign Language) certificate.

English is an obligatory subject from sixth grade across Vietnam, but in large cities, many primary schools demand high (5)______. Foreign language centers have been thriving here, with students as young as three years old.

Điền ô số 4

A. degree    

B. qualification      

C. diploma   

D. level

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 1 to 5.

The invention of the electric telegraph gave birth to the communications industry. Although Samuel B.Morse succeeded in making the invention useful in 1837, it was not until 1843 that the first telegraph line of consequence was constructed. By 1860 more than 50,000 miles of lines connected people east of the Rockies. The following year, San Francisco was added to the network.

The national telegraph network fortified the ties between East and West and contributed to the rapid expansion of the railroads by providing an efficient means to monitor schedules and routes. Furthermore, the extension of the telegraph, combined with the invention of the steam–driven rotary printing press by Richard M. Hoe in 1846, revolutionized the world of journalism. Where the business of news gathering had been dependent upon the mail and on hand–operated presses, the telegraph expanded the amount of information a newspaper could supply and allowed for more timely reporting. The establishment of the Associated Press as a central wire service in 1846 marked the advent of a new era in journalism.

According to the passage, which of the following is NOT true about the growth of the communications industry?

A. Morse invented the telegraph in 1837

B. People could use the telegraph in San Francisco in 1861

C. The telegraph led to the invention of the rotary printing press

D. The telegraph helped connect the entire nation. 

Read the following passage and mart the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 40 to 47.

If you enjoy water sports, Hawaii is the place for you. You can go swimming all year round in the warm water. You can go sport fishing from the shore or from a boat. If you like boats, you can go sailing, canoeing, or windsurfing. Or, you can also try some other water sports that are especially popular in Hawaii: surfing, snorkeling and scuba diving.

Surfing is a sport which started in Hawaii many years ago. The Hawaiians called it “he’e nalu”, which means “to slide on a wave”. If you want to try surfing, you need, first of all, to be a good swimmer. You also have to have an excellent sense of balance. You must swim out from the beach with your surfboard under your arm. When you get to where the waves begin to break, you wait for a calm moment. Then you try to stand up on the board. The wave will begin to rise under you. You must try to steer the board with your feet so you stay on top of the wave. The important thing is to keep your balance and not fall down. If you can manage this, you will have an exciting ride all the way in to the shore.

Scuba diving and snorkeling are two ways to get a close look at the beauty lying below the surface of the ocean. The waters off the Hawaiian Islands are clean, clear and warm. They contain hundreds of kinds of colorful fish. The undersea world is made even more colorful by the coral reefs of red, gold, white and light purple. Among these reefs there may be larger fish or sea turtles.

Scuba diving allows you to see the most interesting undersea sights. “Scuba” means “Self-contained Underwater Breathing Apparatus”, that is, equipment for breathing and swimming around far under water. In Hawaii, you can take special courses to learn how to scuba dive. After the courses, you can get a certificate that will allow you to dive alone. Since it can be dangerous, proper instruction and great care are always necessary when you are scuba diving.

If you are adventurous, you might try snorkeling instead of scuba diving. Less equipment is needed, just a face mask, a breathing tube (snorkel) and flippers for your feet. It only takes a few minutes to learn how to snorkel. Although you cannot dive deep into the water, you can swim with your face below the surface. Breathing through the tube, you float on the surface, and keep yourself moving with your flippers. Even from the surface like this, there will be plenty of color and beauty to see.

The word “this” in the second paragraph refers to _______. 

A. standing on the board 

B. keeping balanced and not falling down 

C. The wave beginning to rise 

D. staying on top of the wave 

Read the following passage and mart the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 40 to 47.

If you enjoy water sports, Hawaii is the place for you. You can go swimming all year round in the warm water. You can go sport fishing from the shore or from a boat. If you like boats, you can go sailing, canoeing, or windsurfing. Or, you can also try some other water sports that are especially popular in Hawaii: surfing, snorkeling and scuba diving.

Surfing is a sport which started in Hawaii many years ago. The Hawaiians called it “he’e nalu”, which means “to slide on a wave”. If you want to try surfing, you need, first of all, to be a good swimmer. You also have to have an excellent sense of balance. You must swim out from the beach with your surfboard under your arm. When you get to where the waves begin to break, you wait for a calm moment. Then you try to stand up on the board. The wave will begin to rise under you. You must try to steer the board with your feet so you stay on top of the wave. The important thing is to keep your balance and not fall down. If you can manage this, you will have an exciting ride all the way in to the shore.

Scuba diving and snorkeling are two ways to get a close look at the beauty lying below the surface of the ocean. The waters off the Hawaiian Islands are clean, clear and warm. They contain hundreds of kinds of colorful fish. The undersea world is made even more colorful by the coral reefs of red, gold, white and light purple. Among these reefs there may be larger fish or sea turtles.

Scuba diving allows you to see the most interesting undersea sights. “Scuba” means “Self-contained Underwater Breathing Apparatus”, that is, equipment for breathing and swimming around far under water. In Hawaii, you can take special courses to learn how to scuba dive. After the courses, you can get a certificate that will allow you to dive alone. Since it can be dangerous, proper instruction and great care are always necessary when you are scuba diving.

If you are adventurous, you might try snorkeling instead of scuba diving. Less equipment is needed, just a face mask, a breathing tube (snorkel) and flippers for your feet. It only takes a few minutes to learn how to snorkel. Although you cannot dive deep into the water, you can swim with your face below the surface. Breathing through the tube, you float on the surface, and keep yourself moving with your flippers. Even from the surface like this, there will be plenty of color and beauty to see.

It can be inferred from the passage that _______. 

A. water sports are all expensive 

B. you need to take serious courses for all water sports

C. everyone can find a way to enjoy sports in the water 

D. swimming in Hawaii can be dangerous