Cho hình phẳng (H) giới hạn bởi Parabol y = x 2 12  và đường cong có phương trình y = 4 − x 2 4 (hình vẽ). Diện tích của hình phẳng (H) bằng

A.  2 4 π + 3 3

B.  4 π + 3 6

C.  4 3 + π 6

D.  4 π + 3 3

Cho biểu đồ:

TỐC ĐỘ TĂNG TRƯỞNG TỔNG SỐ DÂN VÀ SẢN LƯỢNG LƯƠNG THỰC CỦA NƯỚC TA, GIAI ĐOẠN 2005 – 2016

Căn cứ vào biểu đồ, cho biết nhận xét nào sau đây đúng với tốc độ tăng trưởng tổng số dân và sản lượng lương thực của nước ta, giai đoạn 2005 – 2016

A. Sản lượng lương thực và số dân có tốc độ tăng trưởng tương đương nhau.

B. Sản lượng lương thực có tốc độ tăng trưởng thấp hơn tốc độ tăng trưởng số dân.

C. Sản lượng lương thực luôn có tốc độ tăng trưởng cao hơn tốc độ tăng trưởng số dân.

D. Sản lượng lương thực tăng liên tục còn số dân có tốc độ tăng trưởng không ổn định

Tách ra một chùm hẹp ánh sáng Mặt Trời cho rọi xuống mặt nước của một bể bơi. Chùm sáng này đi vào trong nước tạo ra ở đáy bể một dải sáng có màu từ đỏ đến tím. Đây là hiện tượng

A. giao thoa ánh sáng

B. nhiễu xạ ánh sáng

C. tán sắc ánh sáng

D. phản xạ ánh sáng

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.

It is time the government helped the unemployment to find some jobs.

A. time

B. helped

C. unemployment

D. some

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

Before the 1500’s, the western plains of North America were dominated by farmers. One group, the Mandans, lived in the upper Missouri River country, primarily in present – day North Dakota. They had large villages of houses built close together. The tight arrangement enabled the Mandans to protect themselves more easily from the attacks of others who might seek to obtain some of the food these highly capable farmers stored from one year to the next.

The women had primary responsibility for the fields. They had to exercise considerable skill to produce the desired results, for their northern location meant fleeting growing seasons. Winter often lingered; autumn could be ushered in by severe frost. For good measure, during the spring and summer, drought, heat, hail, grasshoppers, and other frustrations might await the wary grower.

Under such conditions, Mandan women had to grow maize capable of weathering adversity. They began as early as it appeared feasible to do so in the spring, clearing the land, using fire to clear stubble from the fields and then planting. From this point until the first green corn could be harvested, the crop required labor and vigilance.

Harvesting proceeded in two stages. In August the Mandans picked a smaller amount of the crop before it had matured fully. This green corn was boiled, dried and shelled, with some of the maize slated for immediate consumption and the rest stored in animal – skin bags. Later in the fall, the people picked the rest of the corn. They saved the best of the harvest for seeds or for trade, with the remainder eaten right away or stored for alter use in underground reserves. With appropriate banking of the extra food, the Mandans protected themselves against the disaster of crop failure and accompany hunger.

The woman planted another staple, squash, about the first of June, and harvested it near the time of the green corn harvest. After they picked it, they sliced it, dried it, and strung the slices before they stored them. Once again, they saved the seeds from the best of the year’s crop. The Mandans also grew sunflowers and tobacco; the latter was the particular task of the older men.

The word “them” in the last paragraph refers to _________

A. women

B. seeds

C. slices

D. the Mandans

Chỉ dùng một hóa chất nào dưới đây thì không thể phân biệt hai dung dịch  C 2 H 2  và HCHO ?

A. Dung dịch  AgNO 3 / NH 3

B. Dung dịch NaOH.

C. Dung dịch  Br 2 / CCl 4

D.  Cu OH 2 / OH -

Read the following passage and mark the letter A, B, C or D on your answer sheet to choose the best answer for each of the question from 43- 50

Of all the aspirations which make up the American Dream, perhaps the most prominent is to own one’s own home. Americans are very proud of their homes and spend a great deal of time maintaining their houses and keeping the property in good condition. A man's home is often called his castle, and the hours spent keeping his fortress safe and secure become one of his greatest pleasures.

If a home is in an especially fashionable neighborhood, the owners may consult an interior decorator to give the home a certain coordinated appearance. If there is a large back yard, great care may be spent in having it properly landscaped with exotic trees, shrubs and plants.

It is almost a certainty that you should be the first visitor to an American home, you will be taken on a grand tour of the premises. The owner will take great pride in showing to you the place he calls home. Every closet, every cabinet and closed door will be opened so that you can actually see the extent and value of his home. You will even be taken into the father's den and the mother's sewing room. These are special rooms for the respective man and woman of the house to insure their privacy. They may be off-limits to the rest of the family but, for the visitor they are open to scrutiny and inspection.

It is, of course, considered polite on the tour to comment favorably on each room picking out its most salient, important feature, such as the special view from the window, the vaulted ceiling in the foyer or the exotic choice of wallpaper in the bathroom.

The finished basement is a special cause for pride for the family with its exercise room, video games, carpenter shop and launderette. In most homes it is here that the family entertains itself in the evening while the rest of the house becomes more of a showcase. On your tour you may be reminded of the hours the owners had spent "fixing up the house" so it would be "nice for the kids to bring over their friends". You may even sense a feeling of competition in knowing that they have not only "kept up with the Joneses" but also have far surpassed them.

The tour will terminate after an hour or so somewhere on the back lawn next to the two-car air-conditioned garage where you may be treated to a snack and light refreshment.

Showing off one's home is more than an exercise in vanity. It is a tribute to one's accomplishment. It is a way of saying that a man has been a good provider for his family and that he has realized one of his dreams.

What is considered polite behavior if you are taken on a grand tour of someone's home?

A. To praise everything you see

B. To listen carefully to everything that is said 

C. To comment favorably on each room

D. To be careful not to break anything

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 44 to 50.

As heart disease continues to be the number-one killer in the United States, researchers have become increasingly interested in identifying the potential risk factors that trigger heart attacks. High-fat diets and "life in the fast lane" have long been known to contribute to the high incidence of heart failure. But according to new studies, the list of risk factors may be significantly longer and quite surprising.

Heart failure, for example, appears to have seasonal and temporal patterns. A higher percentage of heart attacks occur in cold weather, and more people experience heart failure on Monday than on any other day of the week. In addition, people are more susceptible to heart attacks in the first few hours after waking. Cardiologists first observed this morning phenomenon in the mid-1980, and have since discovered a number of possible causes. An early-morning rise in blood pressure, heart rate, and concentration of heart stimulating hormones, plus a reduction of blood flow to the heart, may all contribute to the higher incidence of heart attacks between the hours of 8:00 A.M. and 10:00 A.M.

In other studies, both birthdays and bachelorhood have been implicated as risk factors. Statistics reveal that heart attack rates increase significantly for both females and males in the few days immediately preceding and following their birthdays. And unmarried men are more at risk for heart attacks than their married counterparts. Though stress is thought to be linked in some way to all of the aforementioned risk factors, intense research continues in the hope of further comprehending why and how heart failure is triggered

The word "phenomenon" in line 7 refers to which of the following?

A. habit

B. illness

C. occurrence

D. activity

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.

The concept of obtaining fresh water from iceberg that is towed to populated areas and arid regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being considered quite seriously by many nations, especially since scientists have warned that the human race will outgrow its fresh water supply faster than it runs out of food. Glaciers are a possible source of fresh water that has been overlooked until recently. (A)

        Three-quarters of the Earth's fresh water supply is still tied up in glacial ice, a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1,000 years. Floating on the oceans every year are 7,659 trillion metric tons of ice encased in 10,000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctica. (B)

        Huge glaciers that stretch over the shallow continental shelf give birth to icebergs throughout the year. Icebergs are not like sea ice, which is formed when the sea itself freezes; rather, they are formed entirely on land, breaking off when glaciers spread over the sea. As they drift away from the polar region, icebergs sometimes move mysteriously in a direction opposite to the wind, pulled by subsurface currents. Because they melt more slowly than smaller pieces of ice, icebergs have been known to drift as far north as 35 degrees south of the equator in the Atlantic Ocean. (C)

        The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the funneling of fresh water to shore in great volume. But even if the icebergs lost half of their volume in towing, the water they could provide would be far cheaper than that produced by desalination, or removing salt from water. (D)

What are the technical matters mentioned as the difficulty arising in the process of obtaining fresh water from the iceberg?

A. The prevention of rapid melting iceberg

B. The filtering water and the funneling it to shore in a large amount 

C. The purifying the fresh water and carrying it to shore 

D. The prevention of rapid melting and the funneling to shore in great volume

Mark the letter A, B, C or D on your answer sheet to show the underlined part that needs correction.

The foreign student advisor recommended that she studied more English before enrolling at the university.

A. foreign 

B. studied

C. enrolling

D. the