Tại sao ở hệ tuần hoàn hở máu chảy dưới áp lực thấp?. Tại sao ở hệ tuần hoàn kín máu chảy áp lực cao hoặc trung bình?

Cho hàm số f(x) thỏa mãn ∫ 1 3 f x d x = 5   v à   ∫ − 1 3 f x d x = 1 . Tính tích phân I = ∫ − 1 1 f x d x .

A. I = -4

B. I = -6

C. I = 6

D. I = 4

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 turned the radio on at 7.30. She was still listening to it when her mother came home at 9.00

A. She has been listening to the radio at 7.30

B. She had been listening to the radio since 7.30

C. She has been listening to the radio after 7.30

D. She had been listening to the radio by 7.30

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 a good idea to be careful in buying or purchasing magazines from salespersons who may come to your door.

A. It is

B. to be

C. or purchasing

D. from salespersons

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.

Farmers depend on meteorologists. They need meteorologists’ accurate forecasts for successful agricultural planning.

A. Due to meteorologists’ accurate forecasts, farmers depend on them for successful agricultural planning

B. Farmers depend on meteorologists who need their accurate forecasts for successful agricultural planning

C. Farmers need meteorologists’ accurate forecasts for successful agricultural planning and so they depend on you

D. Farmers depend on meteorologists, whose accurate forecasts they need for successful agricultural planning