The second gap is inside an "island," but the first "licit" gap makes the whole sentence feel okay to a native speaker.
"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
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 .
Once a subject moves to its final position, its internal structure is "frozen" and cannot be accessed. The second gap is inside an "island," but
"*Who did [a picture of ___] hang on the wall?" (The phrase is the subject). Why Do Islands Exist?
"Who did you see [a picture of ___]?" (The phrase is the object). Some violations become acceptable if they are "saved"
A occurs when the grammatical subject of a sentence acts as one of these barriers. In English, you can usually extract a word from the object of a sentence, but doing the same to the subject results in an ill-formed "island violation".