Only in this way can we understand the greatness of nature and the smallness of human beings. According to homework help's query, after seeing the towering mountains, the sentence can be "Only in this way can we understand the greatness of nature and the smallness of people". This sentence expresses people's awe of nature and their understanding of their tiny position in this vast world. The mountain is a part of nature, and its majesty makes people feel the greatness of nature and its own smallness, thus cherishing and respecting nature more. At the same time, this experience also makes people more humble and grateful, realizing that life and existence are endowed by nature, and we should cherish and appreciate nature.