Một âm có tần số xác định lần lượt truyền trong nhôm, nước, không khí với tốc độ tương ứng là v₁, v₂, v_.3. Nhận định nào sau đây là đúng:

A. v₂ >v₁>v₃

B. v₁ >v₂> v_.3

C. v₃ >v₂> v_.1

D. v₂ >v₃> v_.2

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

__________ in UNESCO’s World Heritage Sites in 2003, Phong Nha Ke Bang is noted for its cave and grotto systems.

A. Listing

B. Having listed

C. To have listed

D. Having been listed

Mark the letter A, B, C, or D on your answer sheet to choose the sentence which is closest in meaning to the given one.

“Would you like to come to my birthday party, Sarha?” asked Frederic.

A. Frederic invited Sarha to his birthday party

B. Frederic asked if Sarha was able to come to his birthday party

C. Frederic asked Sarha if she likes his birthday party or not

D. Frederic reminded Sarha of his coming birthday party

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

Question 6: anyone call, please ask them to call back later?

A. If

B. Should

C. When

D. Unless

Cho este no, mạch hở có công thức C_nH_mO₆. Quan hệ giữa n với m là

A. m = 2n.

B. m = 2n + 1.

C. m = 2n – 2.

D. m = 2n – 4.