Mạch điện xoay chiều gồm một cuộn dây có điện trở R, độ tự cảm L nối tiếp với một tụ điện có điện dung C. Các điện áp hiệu dụng ở hai đầu đoạn mạch U   =   120 V , ở hai đầu cuộn dây U D = 120 2 V , ở hai đầu tụ điện U C = 120 V . Tỉ số giữa hệ số công suất của toàn mạch và hệ số công suất của cuộn dây bằng

A.  1 3

B.  3

C.  1 2

D.  2

a) Xét tính liên tục của hàm số y   =   g ( x ) tại x 0   =   2 , biết:  g x   =   x 3 - 8 x - 2   n ế u   x ≠ 2 5   n ế u   x = 2

b.Trong biểu thức g(x) ở trên, cần thay số 5 bởi số nào đó để hàm số liên tục tại  x 0   =   2 .

Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.

Daisy: “What an attractive hair style you have got, Mary!” - Mary: “_______”

A. Thank you very much! I am afraid

B. You are telling a lie

C. Thank you for your compliment!

D. I don't like your sayings

Hãy tìm hai số a và b thỏa mãn 1   <   a   <   b   <   2 , sao cho phương trình trong Ví dụ 3 ở trên có ít nhất một nghiệm thuộc khoảng ( a ;   b ) .

Một khối gỗ có khối lượng  M = 30 k g đặt trên một xe lăn có khối lượng  m = 20 k g đang đứng yên trên sàn nhà (Hình 21.2). Xe bắt đầu chịu tác dụng của các lực có hợp lực là  F = 10 N có phương nằm ngang. Cả xe và gỗ cùng chuyển động tịnh tiến và không địch chuyển so với nhau. Sau bao lâu thì xe đi được 2 m?

A. 4 s.

B. 4,5 s.

C. 5 s.

D. 5,5 s.

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

Dry salt lakes _________ 70 kilometers long and 15 kilometers wide lie _________ long dunes  __________  crests 20 meters high

A. up to / between / with

B. up with / for / to

C. to up / from / for

D. up to/ at/to 

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.

          Living things include both the visible world of animals and plants as well as the invisible world of bacteria and viruses. On a basic level, we can say that life is ordered. Organisms have an enormously complex organization. Life can also “work”. Living creatures can take in energy from the environment. This energy, in the form of food, is changed to maintain metabolic processes and for survival. Life grows and develops. This means more than just getting larger in size. Living organisms also have the ability to rebuild and repair themselves when injured. Life can reproduce. Life can only come from other living creatures. Life can respond. Think about the last time you accidentally stubbed your toe. Almost instantly, you moved back in pain. Finally, life can adapt and respond to the demands placed on it by the environment. There are three basic types of adaptations that can occur in higher organisms.
          Reversible changes occur as a response to changes in the environment. Let's say you live near sea level and you travel to a mountainous area. You may begin to experience difficulty breathing and an increase in heart rate as a result of the change in height. These signs of sickness go away when you go back down to sea level.
          Body- related changes happen as a result of prolonged changes in the environment. Using the previous example, if you were to stay in the mountainous area for a long time, you would notice that your heart rate would begin to slow down and you would begin to breath normally. These changes are also reversible. Genotypic changes (caused by genetic change) take place within the genetic make up of the organism and are not reversible. An example would be the development of resistance to bug-killing chemicals by insects and spiders

Which type of adaptation is permanent?

A. Body- related

B. Reversible

C. Genotypic

D. Environmental

Bánh xe có bán kính R = 50   c m , khối lượng  m = 50   k g (hình vẽ). Tìm lực kéo tối thiểu F nằm ngang đặt trên trục để bánh xe có thể vượt qua bậc có độ cao  h = 30   c m . Bỏ qua ma sát. Lấy g = 10m/s².

A. 2085 N                                               

B. 1586 N                   

C. 1238 N                  

D. 1146 N

Mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that is OPPOSITE in meaning to the underlined part in each of the following questions.

People are now far more materialistic than their predecessors years ago.

A. monetary

B. greedy

C. object-oriented

D. spiritual

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.

          Living things include both the visible world of animals and plants as well as the invisible world of bacteria and viruses. On a basic level, we can say that life is ordered. Organisms have an enormously complex organization. Life can also “work”. Living creatures can take in energy from the environment. This energy, in the form of food, is changed to maintain metabolic processes and for survival. Life grows and develops. This means more than just getting larger in size. Living organisms also have the ability to rebuild and repair themselves when injured. Life can reproduce. Life can only come from other living creatures. Life can respond. Think about the last time you accidentally stubbed your toe. Almost instantly, you moved back in pain. Finally, life can adapt and respond to the demands placed on it by the environment. There are three basic types of adaptations that can occur in higher organisms.
          Reversible changes occur as a response to changes in the environment. Let's say you live near sea level and you travel to a mountainous area. You may begin to experience difficulty breathing and an increase in heart rate as a result of the change in height. These signs of sickness go away when you go back down to sea level.
          Body- related changes happen as a result of prolonged changes in the environment. Using the previous example, if you were to stay in the mountainous area for a long time, you would notice that your heart rate would begin to slow down and you would begin to breath normally. These changes are also reversible. Genotypic changes (caused by genetic change) take place within the genetic make up of the organism and are not reversible. An example would be the development of resistance to bug-killing chemicals by insects and spiders

What does the word “Reversible” in the passage mean?

A. Changeable

B. Visible

C. Fitful

D. Irregular