Một máy bay thực hiện cú nhào lộn biểu diễn, trong thời gian 0,5s nó chuyển động trên cung tròn AB dài 37,5m; bán kính OA 36m.
a. Tính tốc độ trung bình của máy bay trong thời gian trên.
b. Tính vận tốc trung bình của máy bay trong thời gian trên, chọn chiều dương của trục tọa độ từ A --> B.

Tìm x ∈ N  biết:

a) x - 3 : 2 = 5 14 : 5 12 .               b) 30 : x - 7 = 15 19 : 15 18 .      c) x 70 = x .

d) 2 x + 1 3 = 9 . 81 .                      e) 5 x + 5 x + 2 = 650 .                    f) 4 x - 1 2 = 25 . 9  

Người ta cho rằng gen Hb là gen đa hiệu vì:

A.   1 gen Hb nói chung mã hóa 4 chuỗi polipeptit

B.   HbA chỉ có 1 hiệu quả, còn Hb có nhiều tác động

C.   Nó tạo ra sản phẩm gây nên nhiều rối loạn bệnh lý

D.   1 gen Hb gây biến đổi ở 2 chuỗi polipeptit.

This site/ famous/ thrilling/ scenery.

A. This site is famous thrilling scenery.

B. This site is famous as thrilling scenery.

C. This site is famous for thrilling scenery.

D. This site is famous with thrilling scenery.

Choose the letter A, B, C or D to answer these following questions

“The Beauty and the Beast” is a heartfelt story about true love which transforms the Beast into a prince. The fairytale starts with a young girl who lived with her father and two sisters. They lived a good life in a big house but due to some unfortunate turn of events her father lost all his money. They were forced to move into a smaller house. The two sisters kept on grieving for their former life and Beauty kept her sadness for herself and tried her best to help her family.

One day the father found out there is a slight chance he could get back a part of his fortune when one of the ships got back. The two sisters demanded all sorts of thing but Beauty just wanted a single rose. On his way home, the father got lost and wandered into the Beast’s castle. The Beast let him go under the condition of him sending one of his daughters to the castle.

Beauty’s life in the castle was pleasant. She had her room and she was served. Unhappy about his appearance, the Beast never appeared. Beauty only heard his voice. As time passed by they started to love each other. One day, the Beast let her go home to look after her sick father. While she was taking care of her father, she had a dream about Beast dying. When she came back to the palace she found the Beast ill in his bed. She didn’t want him to die and she told him she’ll marry him.

Beast disappeared all of the sudden and its place was taken by a beautiful prince. He told her all about a fairy enchanting him and how the spell could have only been broken by a girl falling in love with him. After her father got better, they threw a wedding and then they all lived happily ever after.

Did the Beast turn into a prince?

A. Yes, he did

B. No, he didn’t

Động cơ của một máy bay có công suất 2 . 10 6 W và hiệu suất 30%. Vậy với một tấn xăng,máy bay có thể bay được bao nhiêu lâu? Biết năng suất toả nhiệt của xăng là 4 , 6 . 10 7 J/kg

A. 2,04h

B. 1,24h

C. 1,92h

D. 2,54h

Biết chu vi đường tròn là C =  36 π (cm) . Tính đường kính của đường tròn.

A. 18(cm)

B. 14(cm)

C. 36(cm)

D. 20(cm)