动词-ing形式作主语和表语 — 英语填空题
题目
用所给动词的适当形式填空（每空只填一个词，须用动词-ing形式）：In the author's travel notes, ___ (hike) across the frozen park in winter demands great courage, and the best part of the journey is ___ (watch) the northern lights light up the night sky, which makes every hour of ___ (wait) in the cold worthwhile.