In 1987, a team from the National Geographic Society drilled a hole through one of the limestone blocks sealing the chamber from above, and inserted a video camera.
1987年，国家地理协会的一组工作人员来在地下室封口的一块石灰石上钻孔，安装了一个录像机。
2
It is the structure characteristics of a solid substrate connection closed sealinghole mesh structure.
它的结构特点是一种固态基质联接的闭封口孔网状结构。
3
First of all the most important point: if the gas pipeline inner fire, immediately closed all into the hole, radiation tube and sealing pipe, and in general to pipe of steam to extinguish fire.