Although the what/how about X construction has been used as a diagnostic tool for topic/comment alignment, its pragmatic functions have not been thoroughly investigated. Previous studies have shown that the topic introduced by the construction contrasts with the topic in the preceding discourse. Li and Liu (2023) question this idea and argue that the construction serves to introduce a topic that is somehow related to the previous context. The question we address in this chapter is how the topic introduced by the construction is related to the previous context. We show that the construction exploits the knowledge shared between the speaker and the hearer to relate the introduced topic to the previous context. Furthermore, we observe that the complement X of the construction is not necessarily anchored to the preceding linguistic context, and argue that the shared knowledge can be formed outside the linguistic context, i.e. the frame semantic knowledge shared by the speaker and the hearer, and the knowledge they form together through the same experience. Our study suggests that linguistic theories must shed more light on the relationship between a construction and its contextual information and that a construction grammar approach is a possible candidate for this purpose.