听力音频：

Questions 31-33

Choose the correct letter, A, B, or C.

31 Caves are A Often ignored. B Mostly in remote areas. C Often difficult to explore.

32 People who explore caves A Mostly need to know about cartography B Enjoy overcoming the difficulties. C Usually know about cave sciences.

33 China has A Probably the most undiscovered caves. B A growing number of cave explorers. C Some of the best documented caves.

Questions 34-40

Complete the table and notes.

Write NO MORE THAN TWO WORDS OR A NUMBER for each answer.

Three Main Reasons for Cave Formation

Dissolution	Volcanic Lava Tubes	Action of Waves
mainly involves 34………………..	topmost surface cools down and 35……………….. hotter lava continue to flow beneath	waves pound in to cliffs then erode into 36……………….. or less rigid rocks.
Limestone caves	often have formations made of 37……………….. carbonate e.g. stalactites, stalagmites, and 38………………..
e.g. Lechuguilla	finally revealed in 39……………….. interestingly, formed from the 40……………….. up