The Great Pyramid is one of the great wonders of the ancient world. There are three large pyramids at Giza, outside the modern capital of Egypt, Cairo. The most famous one is called the Great Pyramid. The workers built it as a tomb（坟墓）for the Pharaoh Khufu（法老胡夫）.

It took more than twenty years to build the Great Pyramid. When it was built, the pyramid was about 146.5 metres high. Over the years it has lost about 10 metres off its top.

The pyramid is made of large stone blocks（石块）— 2, 300, 000 of them! Each of these blocks weighs over 2, 000 kilograms. The ancient Egyptians did not have any modern machines. How did they build the pyramid? The pyramid shows that the ancient people were intelligent and had great skills.

People once thought that the Egyptians made slaves（奴隶）do all the work on the Great Pyramid. But in fact, they used farmers.

①If a child has brown hair and blue eyes, one or both of the child’s parents probably has brown hair and blue eyes. Why? Genes (基因). Scientists know that the way people look is passed down from parent to child by information in genes. But how about other things? If a parent is shy, then would the child also be shy? If a parent is smart, then will the child also be smart? Scientists want to know how much genes and ways of raising can affect (影响) a person.

②One way scientists have studied this question is by studying identical twins who were separated (分开) at birth. Identical twins are twins that look the same on the outside. They also have the same genes on the inside. This is how scientists study their nature. Many years ago, when twins were given away to other families at birth, they didn’t always go to the same family. So, they were separated and raised in different ways. This was of great interest to scientists. Even if the twins had the same genes and looked the same, did they turn out the same as adults? Here are what the scientists have found.

③For some things, such as looks or diseases, the twins turned out the same. Even if one twin drank lots of milk and the other did not, they were of similar heights as adults. Even if one twin exercised and ate healthy food and the other did not, they could get the same disease as adults. Scientists found that how each twin was raised could not change much.

④However, in the case of personality (个性), the answer is not so clear. Some separated twins had completely different personalities and lives as adults. Other separated twins were almost exactly the same. They dressed the same, talked the same, and even had the same jobs—even though they had never met!

⑤In the end, there seems to be no simple answer. As a whole, it seems people become who and what we are because of both genes and how we are raised.

TV Ears has helped thousands of people with various degrees of hearing loss hear the television clearly. When using it, you needn’t turn up the volume of TV. And now it’s better and more affordable than ever! With TV Ears wireless technology, you set your own headset volume, while other TV listeners hear the television at a volume level that’s comfortable for them. You can even listen through the headset only and put the TV on mute if the situation calls for a quiet environment.

TV Ears can reduce outside noise so that television dialogue is clear and understandable. That’s why it has earned the trust and confidence worldwide.