Briefly talk about the formal characteristics of Yuan dramas

Yuan Zaju, also known as Northern Zaju, was developed on the basis of Zhugong Harmony and Jinyuan, and is composed of "four folds and one Qizi". Zhe is a unit of music. One Zhe uses a set of tunes from the same palace tune, and Four Zhe is the four major sets of tunes. In the performance, one person sings the lead. For example, in a play mainly featuring Zhengdan, only Zhengdan sings to the end, and other roles do not sing, only Binbai is used. This is a transformation from the form of Zhugong Diao where an actress and an actor sing solo. came.