阅读下面短文, 在空白处填入1个适当的单词或括号内单词的正确形式.

A visually-challenged man from Beijing recently hiked (徒步) 40 days to Xi’an, as a first step _ 41 _ (journey) the Belt and Road route (路线) by foot.

On the 1,100. Kilometer journey, the man Cao Shengkang, _ 42 _ lost his eyesight at the age of eight in a car accident, crossed 40 cities and counties in three province. Inspired by the Belt and Road Forum for International Cooperation _ 43 _ (hold) in Beijing, Cao decided to cover the route by hiking as a tribute (致敬) to the ancient Silk Road. _ 44 _ friend of his, Wu Fan, volunteered to be his companion during the trip.

Cao and Wu also collected garbage along the road, in order to promote environmental _ 45 _ (protect). Cao believes this will make the hiking trip even more _ 46 _ (meaning). The two of them collected more than 1,000 plastic bottles along the 40-day journey.

In the last five years. Cao _ 47 _ (walk) through 34 countries in six continents, and in 2016, he reached the top of Kilimanjaro, Africa’s _ 48 _ (high) mountain.

Now, Cao has started the second part of his dream to walk along the Belt and Road route. He flew 4, 700 kilometers _ 49 _ Xi’an to Kashgar on Sept. 20, _ 50 _ (plan) to hike back to Xi’an in five months.