A、To water plants. B、To feed animals. C、To take adventure alone. D、To treat nature with respect. D短文中提到，the National Park Servic

Camping can teach you many things, such as how to recognize plants and animals, to set up a tent and to read a map. Most of all, you can anticipate understanding more about yourself and your place in nature.
    Whether you decide to travel on foot into the wilderness, to travel by canoe, or simply to drive to a nearby camp ground, you are probably looking for some of the same experiences. Most campers hope to find a simpler lifestyle. They tend to forget about work and worries while they enjoy being outdoors.
    Because the number of the U. S. campers is increasing daily, the National Park Service advises outdoor lovers to remember several things. First, although it encourages campers to enjoy the outdoors, it urges everyone to treat nature with respect. That involves leaving your campsite cleaner than you found it. It involves learning to enjoy the natural world of plants and animals without disturbing it. Remember that wild animals are wild, and they can hurt you, just as you can hurt them.
    The park service invites you to enjoy and explore the world of nature, but at the same time, it expects you to protect each area you visit so that future generations may look forward to having similar enjoyable experiences.
Questions 26 to 29 are based on the passage you have just heard.
26. What is the main purpose for camping?
27. What do most campers look for?
28. What does the National Park Service urge the campers to do?
29. What is the main purpose of the speaker?