Islands -

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

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

Once a subject moves to its final position, its internal structure is "frozen" and cannot be accessed. "Which book did you file ___ [without reading ___]

"*Who did [a picture of ___] hang on the wall?" (The phrase is the subject). Why Do Islands Exist? known as a .

Not all subject islands are equally strong. Some violations become acceptable if they are "saved" by a second gap in the sentence, known as a .