Tìm số nguyên x, biết  − 12 27 + 2 3 + − 2 9 ≤ x ≤ 11 7 + 2 5 + − 7 5 + 3 7

a) Hãy lập các cặp phân số bằng nhau từ đẳng thức:

2.4 = 1.8

b) Hãy lập các cặp phân số bằng nhau từ đẳng thức:

(-4). 6 = 3.(-8).

Biết độ dài ba cạnh của một tam giác tỉ lệ với 5,6,7 và chu vi tam giác bằng 36. Tính độ dài cạnh lớn nhất của tam giác đó

A. 10

B. 12

C. 14

D. 18

Read the passage and check (ü) whether the following statements are true (T) or false (F).

Energy makes change; it does things for us. It moves cars along the road and boats over the water. It bakes a cake in the oven and keeps ice frozen in the freezer. It plays our favourite songs on the radio and lights our homes. Energy makes our bodies grow and allows our minds to think. Scientists define energy as the ability to do work. People have learned how to change energy from one from one form to another so that we can do work more easily and live more comfortably.

All forms of energy are stored in different ways, in the energy sources that we use every day. These sources are divided into two groups – renewable and nonrenewable. Renewable energy source is an energy source that can be replenished in a short period of time. Nonrenewable energy source is an energy source that we are using up and cannot recreate in a short period of time.

Renewable energy sources include solar energy, which comes from the Sun and can be turned into electricity and heat. Wind, geothermal energy from inside the Earth, biomass from plants, and hydropower and ocean energy from water are also renewable energy sources.

However, we get most of our energy from nonrenewable energy sources, which include the fossil fuels – oil, natural gas, and coal. They’re called fossil fuels because they were formed over millions and millions of years by the action of heat from the Earth’s core and pressure from rock and soil on the remains of dead plants and animals. Another nonrenewable energy source is the element uranium, whose atoms we split (through a process called nuclear fission) to create heat and ultimately electricity.

Question: Renewable energy can be turned into electricity and heat.

A. True

B. False

Việc sáng tạo ra chữ viết của các cư dân cổ đại không mang ý nghĩa nào sau đây?

A. Là thước đo đánh giá trình độ nền văn minh

B. Giúp lưu giữ thông tin

C. Là cơ sở để truyền bá văn hóa rộng rãi

D. Là cơ sở quan trọng tạo ra lịch pháp