Advanced learners use the progressive to downplay commitment ( “I was thinking we might…” ) or to add vividness to narrative ( “So, he is walking into the room, and everyone is staring…” ).
The book is distinguished by several pedagogical characteristics:
The addition of "possibly" and the past form "could" does not refer to past time. Grammatically, it creates "social distance." It makes the request softer and less imposing. Advanced grammar involves mastering these "remote" forms to navigate power dynamics and politeness.
Moving from "Correct" to "Natural": The Advanced Learner's Guide to Communicative Grammar
Most advanced learners know the 12 tenses. What they often miss is the communicative effect of choosing one tense over another.