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Baotrue123
2 năm trước
a) S= 3 + 6 +9+12 +......+ 2001 b) tổng các số lẻ có 2 chữ số tính tổng nhanh nha
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VII. Read the following passage, and then tick the correct answers: true (T), or false (F). Most of the world’s energy comes from the sun. The sun’senergy is in wood, oil, and other things that people use for energy. People use many sources of energy. Ancient people used only their arms, hands and simple tools until they discovered fire. Later, people learned to use the energy of the wind to sail ships. Then they learned to use animals to do work. In the 18th and 19th centuries, people began to use machines. The first machines used steam. They burned coal to heat water. The hot water turned into steam, and the steam engine did the work. Later, people began to use the gasoline engine, and today people are using nuclear energy. Energy is one of the basic concepts, or ideas, or physics. It is the ability to do work. Without energy we could not live. We need energy to work, and scientists are always looking for new sources of energy. 61. None of the world’s True False energy comes from the sun 62. Wind, steam, and gasoline are sources of energy. 63. People have never used nuclear energy. 64. Energy is the ability to do work. 65. We need new sources of energy.

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