Calendar query 196 1 Why is heavenly stems and earthly branches different in May?

Watching the perpetual calendar has a characteristic. The trunk marked by the perpetual calendar is not necessarily this trunk, but only helps the user to judge the trunk. It's a bit inappropriate to say "the moon in the morning" or "the moon in the morning". The judgment of the month lies in the festival, not whether it depends on the lunar month. Why the May of the question does not match heavenly stems and earthly branches, or whether it has entered a vertical node, or belongs to the same question. For example, when you enter the Qingming vertical node, the main branch is the moon, and people who have not yet entered the vertical node belong to Uzuki. or vice versa, Dallas to the auditorium