Tất cả các giá trị của a để hàm số  y = x 3 + x 2 + a x  đồng biến trên R là

A . a ≥ 1 3

B . a ≥ 0

C . a < 0

D . a > 1 3

Để hoàn thành cuộc cách mạng dân chủ nhân dân, các nước Đông Âu đã thực hiện những nhiệm vụ gì?

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

The children had been_____of the danger, but had taken no notice.

A. warned

B. explained

C. shown

D. prevented

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

Valentine’s Day, _______ from Roman, is now celebrated all over the world.

A. originate

B. originating

C. to originate

D. originated

Mark the letter A, B, C, or D to indicate the sentence that best completes each of the following exchanges.

Two friends are talking about their lives:

X: “I feel really depressed at the moment. Nothing's going right in my life.”

Y: “__________.”

A. I know. We really need some sunshine, don't we? 

B. Cheer up! Things can't be that bad! 

C. I'm sorry to hear that, but I'm sure he'll be all right. 

D. That's good. I'm pleased to hear it.

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