47. ___
A. She was asked to lead a group of inexperienced cavers there.
B. It was the first cave that she had ever visited.
Clearly marked trails mode it easy to explore.
D. She hoped to make a discovery.
48. ___
A. It’s easy to locate.
B. It’s in a very windy area.
C. It’s exceptionally beautiful.
D. It’s partially covered by water.
49. ___
A. They are more likely to damage the cave.
B. It’s hard for them to stay awake.
C. They tend to break their equipment.
D. They may imagine seeing things that aren’t really there.
50. ___
A. They are newer than the formations in most caves.
B. They were formed by sulfuric acid.
C. They have been artificially preserved.
D. They are smaller than those in any other cave.
40. ___
A. Competition in business.
B. Government grants.
C. A type of economic policy.
D. International transportation practices.
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