What techniques have been used to cover the mountains and rivers of our country over three thousand miles in the past forty years?

Time and space competition.

Our country has been three thousand miles away and we have three rivers in the past forty years. This sentence uses the rhetorical technique of parallelism between time and space. The first half of the sentence describes our home and country over the past forty years, and the second half describes our country three thousand miles away. The mountains and rivers of the country create a contrast in time and space between the country and the country.

Time and space antithesis means that poets describe scenery from two perspectives: time and space to create artistic conception. This technique is often used in ancient poetry to achieve the purpose of combining virtuality and reality.