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 Atlantic Ocean is the second largest ocean in the world, covering about 20 percent of the earth's surface. It separates Europe and Africa to the east from North and South America to the west. Its name, which comes from the Greek, probably refers to Atlantis, the legendary island continent said to have been the site of a great civilization before the island suddenly disappeared.
The Atlantic extends from the Arctic Ocean in the north to Antarctica in the south. It is over 16, 000 kilometers long and between 2, 900 kilometers and 8, 500 kilometers wide. The area of the Atlantic is about 106, 464, 000 square kilometers. Its average depth is around 3, 300 meters, and the maximum depth is 8, 380 meters in the Puerto Rico Trench, north of the island of Puerto Rico.
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