阅读下列短文, 从每题所给的A、B、C、D四个选项中选出最佳选项。
A
Join a Zion National Park ranger（护林人）to learn about what makes Zion National Park unique. Programs are free and created for classrooms and individuals. We connect to your school or home through a free web-based program. You will be provided with a link to the video conference ahead of time via an email invite. Registration is open! Click on the program below for more information.
Program 1—Chat with a Ranger
In Chat with a Ranger, students learn about Zion National Park, the park service, and the life of a ranger. Students prepare and send questions ahead of time. This program can be adapted to fit different curriculum objectives, and is appropriate for any age group.
Program 2—Pollination Investigation
In this distance learning program, students will discover what pollination is and how important it is to all ecosystems. Looking at the relationship between plants and pollinators, participants will see how they have influenced each other and will be challenged to create their own perfect pollinator.
Program 3—Whooo's in the Canyon?
Who left these clues behind here in the high canyons of Zion National Park? A feather, small bones, and hoot hooting in the trees can be heard as your classroom goes on a virtual hike of Zion to discover the Mexican spotted owl. Learn it about how the owl uses its special adaptations to survive in this desert environment.
Program 4—The Forests, Wetlands, and Deserts of Zion
This distance learning program focuses on the plants and animals that live in Zion's varying ecosystems. Students will learn about their adaptations and relationships to each other in this interactive lesson with a creative and critical thinking activity.
21. Which program requires participants to make preparations in advance?
A. Chat with a Ranger. B. Pollination Investigation.
C. Whooo's in the Canyon? D. The Forests, Wetlands, and Deserts of Zion.
22. What can participants learn from program 3?
A. Survival strategies taken by owls in the park.
B. Ways to prepare a hike tour in the park.
C. Threats brought by the desert environment.
D. A variety of ecosystems in Zion National Park.
23. What do the listed programs have in common?
A. They involve interactive activities.
B. They include a virtual tour of different trails.
C. They are accessible through web-based program.
D. They require participants to visit the park in person.
