Islands ✮

The second gap is inside an "island," but the first "licit" gap makes the whole sentence feel okay to a native speaker.

Linguists debate whether these "walls" are built into our mental grammar or caused by how we process information. 1. The Architectural View Islands

Subjects usually provide "old" information (the background). Trying to pull a "new" focus out of a backgrounded subject creates a mental clash. The second gap is inside an "island," but

"Which book did you file ___ [without reading ___]?" Islands

Modern theories suggest certain phrases are "phases" that become invisible to the rest of the sentence once completed. 2. The Information Structure View

Extracting from a subject might simply be too mentally taxing for the brain to process in real-time. Exceptions and "Parasitic" Gaps