Năng lượng cần thiết của người lớn trong thời gian một ngày khoảng bao nhiêu?

A. 50 kcal/kg trọng lượng cơ thể/ngày

B. 100 kcal/kg trọng lượng cơ thể/ngày

C. 150kcal/kg trọng lượng cơ thể/ngày

D. 200 kcal/kg trọng lượng cơ thể/ngày

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions from 5 to 16.

They'll be able to walk across the river______.

A. if the ice is thick enough

B. if the ice will be thick enough 

C. when the ice will be thick enough  

D. unless the ice is thick enough

Trong hình 68, đường tròn tâm O có bán kính R = 2cm, góc AOB = 75o.

Tính sđ  A p B ⏜

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.

 Millions of people are using cellphones today. In many places, it is actually considered unusual not to use one. In many countries, cellphones are very popular with young people. They find that the phones are more than a means of communication - having a mobile phone shows that they are cool and connected.

 The explosion in mobile phone use around the world has made some health professionals worried. Some doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.

 On the other hand, medical studies have shown changes in the brain cells of some people who use mobile phones. Signs of change in the tissues of the brain and head can be detected with modern scanning equipment. In one case, a traveling salesman had to retire at young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't agree.

 What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.

 As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often.
Question:According to the passage, people should _______.

A. only use mobile phones in medical emergencies

B. never use mobile phones in all cases

C. only use mobile phone in urgent cases

D. keep off mobile phones regularly

Trong nguyên tử hiđrô, bán kính Bo là r 0 = 5 , 3 . 10 - 11 m. Ở một trạng thái kích thích của nguyên tử hiđrô, êlectron chuyển động trên quỹ đạo dừng có bán kính là r   =   2 , 12 . 10 - 10 m. Quỹ đạo đó có tên gọi là quỹ đạo dừng

A. N

B. M

C. L

D. O

Một thanh kim loại CD dài l=20cm chuyển động trong từ trường đều với vận tốc không đổi v=1(m/s) theo hướng vuông góc với thanh, cắt vuông góc với các đường cảm ứng từ có B=0,3T. Cho điện trở của điện kế là R A = 2 Ω . Tính cường độ dòng điện qua điện kế và chỉ rõ chiều dòng điện ấy.

A. 0,03A, từ C đến D

B. 0,03A, từ D đến C

C. 0,06A, từ C đến D

D. 0,06A, từ D đến C

Dung dịch axit fomic bị khử trong phản ứng với

A. NaHCO₃

B. Nước brom

C. Zn

D. AgNO₃ trong dung dịch NH₃

Cho mạch điện như hình, U_AB = 9V; E = 3V; r = 0,5Ω; R 1  = 4,5Ω; R 2  = 7Ω. Cường độ dòng điện trong mạch là

A. 0,5A                           

B. 1A

C. 1,5A                         

D. 2A

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 following questions

Fish that live on the sea bottom benefit by being flat and hugging the contours. There are two very different types of flatfish and they have evolved in very separate ways. The skates and rays, relatives of the sharks have become flat in what might be called the obvious way. Their bodies have grown out sideways to form great “wings” They look as though they have been flattened but have remained symmetrical and “the right way up”. Conversely fish such as plaice, sole, and halibut have become flat in a different way. There are bony fish which have a marked tendency to be flattened in a vertical direction; they are much “taller” than they are wide. They use their whole vertically flattened bodies as swimming surfaces, which undulate through the water as they move. Therefore when * their ancestors migrated to the seabed, they lay on one side than on their bellies. However, this raises the problem that one eye was always looking down into the sand and was effectively useless - In evolution this problem was solved by the lower eye “moving” around the other side. We see this process of moving around enacted in the development of every young bony flatfish. It starts life swimming near the surface, and is symmetrical and vertically flattened, but then the skull starts to grow in a strange asymmetrical twisted fashion, so that one eye for instance the left, moves over the top of the head upwards, an old Picasso - like vision. Incidentally, some species of 20 flatfish settle on the right side, others on the left, and others on either side.
Question:The author mentions skates and rays as examples of fish that ____

A. become asymmetrical

B. appear to fly

C. have spread horizontally

D. resemble sharks