2.cave art in Western Europe
3.Grotte de Font-de-Gaume
4.Some caves were used as temples.
5.hollow out as if making a cavern.
6.If no remedial measures are taken, the upper layer grottoes are bound to become open-air.
7.Only success in controlling the water can deliver the caves from danger.
8.a small cave (usually with attractive features).
9.Many caves in Mogao Grottoes have a series of pictures telling stories.
10.In some grottoes, there are as many as three mural layers.
