We started to use a simple clinometer, graphical reduction of distance to draw maps in caves.我们开始使用一种简单的测斜器, 减少图解距离,并绘制出关于凹陷的地图.The caves extend for some 18 kilo-metres.那些洞穴深约18公里。The caves extend for some 18 kilometres....
The caves extend for some 18 kilo-metres.那些洞穴深约18公里。The district is pock-marked with caves.这个地区布满了坑洞。Walkways allow visitors to enter the caves in perfect safety.步行道使游客可以十分安全地进入那些洞穴....