Trong quá trình nguyên phân thoi vô sắc là nơi

A. Gắn nhiễm sắc thể

B. Hình thành màng nhân và nhân con cho các tế bào con

C. Tâm động của nhiễm sắc thể bám và trượt về các cực của tế bào

D. Xảy ra quá trình tự nhân đôi của nhiễm sắc thể

Tìm thể tích của hình chóp S.ABC biết  S A = a , S B = a 2 , S C = 2 a  và có  B S A ^ = 60 ° ,   B S C ^ = 90   ° , C S A ^ = 120 °  

A.  a 3 6 12

B.  a 3 2 3

C.  a 3 3 6

D.  a 3 3

Trong các biện pháp ngăn ngừa virus máy tính dưới đây, biện pháp nào kém hiệu quả nhất

A. Không dùng phần mềm có nguồn gốc không rõ ràng

B. Khi dùng lại đĩa mềm thì pahỉ khởi tạo lại đỉa đó

C. Không dùng chung một đĩa mềm cho nhiều máy tính

D. Khi muốn sử dụng phần mềm ghi trên đĩa mềm thì sao chép nó sang đĩa cứng rồi mới sử dụng

Văn bản “Mẹ tôi” được viết theo phương thức biểu đạt nào?

Choose the word or phrase among A, B, C or D that best fits the blank space in the following passage.

Neil Armstrong was the first person (1)…….. on the moon. He was born in Ohio on August 5, 1930. While he was in college, he left to serve in the U.S. Navy. He flew planes during the Korean War. Then he came back to college and finished the degree he (2)……... He later (3)…….. a master's degree too. Armstrong became an astronaut in 1962. He was the commander of Gemini 8 in 1966. Neil Armstrong (4)…….. the first successful connection of two vehicles in space. Armstrong’s second flight was Apollo 11 in 1969, and he was the mission commander. He flew with Buzz Aldrin and Michael Collins. Armstrong and Aldrin landed on the moon in a lunar module named "Eagle". With more than half a billion people (5)…….. on television, Armstrong (6)……… the ladder and said, "That's one small step for a man, one giant leap for mankind." and Aldrin (7)……. him shortly. They explored the surface for two and a half hours, collecting samples and taking photographs. They left behind an American flag, and a plaque reading, "Here men from the planet Earth first (8)………..upon the moon. July 1969 A.D. We came in (9)…….for all mankind." After almost a day, they blasted off. They docked with Collins in (10)……….around the noon. All three then flew back to the Earth.

Điền vào số 1

A. walk

B.walking

C.to walk

D.walked

Read passage and then decide whether the sentences are True or False.

The Clock Tower of the Palace of Westminster - officially named Saint Stephen's Tower - is commonly known as the Big Ben. It is one of London's most famous landmarks. The clock inside the tower was installed in the middle of the nineteenth century. It is the largest clock in the world. The name Big Ben actually refers to the largest of the clock's five bells. The clock faces have a diameter of almost 7.5m. The hour hand is 2.7m long and the minute hand measures 4.25m long. The clock, designed by Edmund Beckett Denison, has a remarkable accuracy. It is known for its reliability because it has rarely failed during its long life span. Even after the nearby House of Commons was destroyed by bombing during World War II, the clock kept on chiming.

Saint Stephen's Tower is the largest tower in the world.

A. True

B. False

Vì sao các nhân vật trong truyện sợ sệt, lo lắng khi nhìn cây thường xuân trong văn bản “Chiếc lá cuối cùng”?