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1.tính nhanh352+65+647,51= 0,382+100+9618= 200-72,28-27,77= 1053-8,512-1,488= 2.dưới
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People invent things to enhance their lives. Today, inventions are mostly improvements of previous inventions. With technology, inventions are taking a shorter and shorter time to complete. One such invention is the camera. The time taken to invent the camera in the sixteenth century was prolonged due to the lack of technology and scientific knowledge. When inventors first tried to take a photograph in 1558, the image could not stay on the paper permanently. It was only in 1837 that inventors managed to produce pictures that did not fade away. With the invention of the camera, further improvements were made and the first underwater camera was invented in 1856. It was placed in a tightly sealed container. However, when the contraption was underwater, the container broke before many pictures were taken. It was only in the 1980s that a camera was made to be able to go deep underwater without being damaged. Less than twenty years later, technology allowed underwater cameras to take photographs in color and to go even deeper into the water. The cameras even looked like a fish. With better technology, an invention will never stay stagnant. People will be relentless in their efforts at making improvements to an invention. 28 How are inventions of today different from those in the past? A. They have intention of being larger. B. They are effectively used. C. They gradually enrich people’s lives. D. They need less time to complete. 29 What happened to the image on the photograph of the first camera? A. The color of image did not stay a long time. B. The image was different after a time period. C. The image could not remain on the paper for long. D. The image disappeared. 30 How many years later did it take the inventors to produce the first underwater camera after the first camera? A. 298 years B. 389 years C. 321 years D. 279 years 31 The first underwater camera was ________. A. made after one improvement B. put in a container C. covered with a seal D. stuck to a box 32 How was the underwater camera in the 1980s different from the previous? A. It could take color photos and go deeper. B. It took color pictures without going into water. C. It had the shape of fish. D. It could swim like á fish.

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