互动封闭仿真课堂
1、智能交互 2、电子板书式视频教学 3、在线互动问答 4、封闭课堂启发式教学方式
随堂测试、知识梳理、易错点揭示、总结启迪智能错题本
听课中的错题能自动加入错题本，课后可方便复习及导出错题本升级服务
在线答疑、课后同类题练习、讲义下载、短信提醒THE GREAT PYRAMID
It's very hard to realize just how big the Great Pyramid is. It has over 2 300 000 blocks of solid stone. These huge stone blocks weigh an average of two and a half tons each, as much as a small car. Some even weigh fifteen tons. Without machinery, the ancient Egyptians cut and moved and lifted each of these stones. The blocks came from the east bank of the Nile. Slaves took them across the Nile in boats at flood time. It took more than 100 000 slaves twenty years to build the Great Pyramid.
The Great Pyramid is over 450 feet high today, and it was once higher. Its base covers thirteen acres. Each of the sides of the pyramid is 755 feet long, or about as long as two city blocks. It takes about twenty minutes to walk all the way around the pyramid.
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