Instead our approach is to address the problem by exploiting the structure of reading comprehension questions, a typical language learning task: Students' answers are linked to a reading text in standard language; when students answer reading questions, they rely on the given textual material and tend to repeat words or even copy whole phrases from the question or the reading text (referred to as reference texts below), a phenomenon known as lifting.
learner answers tend to have a high lexical overlap with the reference texts.