Expressions of modality are often treated as interpersonal resources that indicate the speaker’s modal assessment of the proposition.This paper argues that,expressions of modality,apart from functioning as interpersonal expressions,also have a role in the logical metafunction.They can serve in the clause complex of Chinese as conjunctive markers to indicate the logico-semantic relation of expansion.As conjunctions are the congruent marker of logico-semantic relations,expressions of modality can be viewed as “marked” markers of logico-semantic relations. Expressions of modality are often treated as interpersonal resources that indicate the speaker’s modal assessment of the proposition. This paper argues that, expressions of modality, apart from functioning as interpersonal expressions, also have a role in the logical metafunction. They can serve in the clause. complex of Chinese as conjunctive markers to indicate the logico-semantic relation of expansion. As conjunctions are the congruent marker of logico-semantic relations, expressions of modality can be viewed as “marked ” markers of logico-semantic relations.