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.

He was able to finish his book. It was because his wife helped him.

A. If only he had been able to finish his book.

B. If it weren’t for his wife’s help, he couldn’t have finished his book.

C. Without his wife’s help, he couldn’t have finished his book.

D. But for his wife’s help, he couldn’t finish his book.

Một vật được ném thẳng đứng lên cao từ mặt đất với vận tốc đầu 4 m/s. Bỏ qua sức cản không khí. Tốc độ của vật khi có động năng bằng thế năng là

A.  2 2   m / s

B. 2 m/s.

C.   2   m / s

D. 1 m/s.

Đồ thị hàm số y   =   - x 4 + 2 x 2  có bao nhiêu điểm chung với trục hoành?

A. 0

B. 2

C. 3

D. 4