From ancient times to the present, leveling and tones have been important in poetry (including tones in prose sentences and idioms, colloquial tones in colloquial sayings, etc.). However, the four tones of Mandarin are based on the four tones of yin and yang of modern northern spoken language, which are very different from the four tones of ancient times.

The four tones of the couplets use the ancient four tones, which were originally based on the spoken language of the Tang Dynasty and were finally fixed through official rhyme books such as "Peiwen Shiyun". Among them, the flat sound is flat, and the straight sound is flat. We learn to compose couplets, and the leveling and leveling should always be based on the four ancient tones. Because this is the only standard that countless authors have adhered to when writing couplets for hundreds or even thousands of years.