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khanhle2399
2 năm trước
Cho1 đèn , 1nguồn điện , công tắc và dây dẫn . a. Vẽ sơ đồ mạch điện và xác định chiều dòng điện?. b. Khi đóng công tắc mà đèn vẫn không sáng . Nêu hai trong số những chổ hở mạch và cho biết cách khắc phục ?
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Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions. Inventions That Changed Our World People have been inventing things for years. Paper was invented about 2,000 years ago. The wheel was invented more than 5,000 years ago. What would life be like without paper to write on or bikes to ride? Those inventions have made life easier. Airplane The Wright Brothers invented the first airplane in December 1903. That makes 2003 the 100th anniversary ! Before the airplane was invented, most people traveled by cars, boats, and trains. Today, airplanes help people travel faster. How do airplanes help you? Telephone Alexander Graham Bell invented the telephone in 1876. Before the telephone was invented, people kept in touch by writing letters or talking in person. Today the telephone makes it easier for people to talk to one another. How do telephones help you? Automobile The first four-wheeled gas-powered car was invented by Karl Benz in 1891. Before people had cars, they couldn’t travel easily. They walked or rode horses for short trips. They took trains or boats for long trips. Today cars are one of the main ways people travel. How do cars help you? Computer People worked for years to make the first computer. It was built in 1946. The first computer was called ENIAC. Today computers are an important part of many people’s lives. People use computers as tools to write, get information, and much more. How do computers help you? Question 21. The primary purpose of this passage is to describe ________. A: some inventions that have made a big difference. B: the invention of the airplane in December 1903. C: the reasons why Karl Benz invented the gas-powered car. D: some ways that computers help to make our lives easier.

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