On each of the 20 sides is an answer to a yes-or-no question.

这20 个面的每一面上都是一个问题的答案，答案只有是或否两种。

The yes-no question is an important type of the interrogative sentence in modern Chinese, and massive outstanding achievements related to this have emerged.

是非问句是现代汉语疑问句的一个重要类型，相关的研究已经涌现出大量优秀的成果；