根据短文理解，完成下列各题。
Thousands of years ago, the kings of Egypt built strong tombs for themselves. Over these tombs they built pyramids. They thought their bodies would be well kept in these tombs until they could come back to life. They also hoped the world would look on the pyramids as monuments to them and would remember them forever.
There are about 80 pyramids in Egypt. But the Great Pyramid is the biggest of all. It is nearly 5, 000 years old. It is about 137 meters high today, but it was once higher. It is made of 2, 300, 000 huge stones. Most of them are higher than a man and weigh about two and a half tons each. Some weigh as much as fifteen tons. It took more than 100, 000 men twenty years to build the Great Pyramid.
When you look at the pyramids, you can't help wondering how the Egyptians were able to build them thousands of years ago. How did they cut, carry and lift such huge stones? Each stone fits so well, yet they didn't have our modern machines! Scientists have studied the pyramids, but nobody can tell just how the Egyptians built them so long ago.
Inside the pyramids are the rooms for the bodies of the kings and queens. There are lots of wonderful treasures in the pyramids, too. Thieves have broken into some of the pyramids and taken away many of the treasures to foreign countries. They have even stolen the mummies. Today some of the mummies and treasures are on show in museums in different countries. When the kings had the pyramids built for them, they perhaps never thought this would happen.