Most students, when asked about their ideal graduation gift, would probably reply, "A car", or "Money for a deposit on a house". Cai Kaiyuan, 21, made a different choice. As a graduation gift to himself, he decided to work as a volunteer teacher in a remote village in Tibet. Cai, a senior majoring in electrical engineering at Huan Railway Professional Technology College, originally planned to cycle from Sichuan to Tibet. During his journey, Cai's idea for a different graduation gift to himself began to take shape. "I did not know beforehand what the journey would mean to me. I just want to gain a unique experience and have pleasure in appreciating the view there," he said. It turned out cycling on a plateau was extremely challenging. And it has kept changing his outlook on life. Cai's fingers even became frostbitten while cycling up a 5008-meter-high mountain, where temperatures often dropped to 18 below zero. At night, the ice covered the road and he fell off his bike three times. The lack of oxygen made him feel dizzy and weak. "At the most serious moment, I felt that my life was _ ," said Cai. However, he also gained something unexpected. At Ya'an, a city in Sichuan, he met a group of tourists who are also university students. A girl called Wu Ling told him that she planned to work as a teacher in a primary school in Tibet after her journey. He was impressed by the idea as she looked slender and weak. It was not until he reached a family-run hotel in Shigatse that Cai's spirits began to rise. The hotel manager's two daughters enjoyed talking with him. The kids asked about his experiences on his trip, and showed him the beautiful local lakes. "They told me that they always liked to talk to guests, as they wanted to improve their Mandarin," he said, "Their parents and many locals can only speak Tibetan." Cai was touched by the girls' story. Their situation is tough and the local people have little chance to learn Mandarin because the schools are short of teachers. "I want to do something to improve the situation for kids like them," said Cai. His parents finally gave their agreement and his teachers also supported him. What words can be used to describe Cai's journey to Tibet?
unique and pleasant challenging but rewarding relaxing but unexpected freezing cold and boring