Different types of modal adverbs have different sematic structures, some part (s) of which can be left out in certain contexts, and become presupposition triggers.

• 该预设是一种语用预设，表明了命题在语言交际中的适切性。不同类别的语气副词拥有不同的语义结构，该结构的某一部分在一定的语境中可以隐含，成为语气副词的预设。