我们想去喜马拉雅山徒步旅行。

We want to go ___trekking in the Himalayas.

我听说她要去非洲徒步旅行。

I hear she's going to Africa for some ___trekking.

穿越雨林徒步旅行需要良好的体能。

___Trekking through the rainforest requires good physical fitness.