Task: Question Answering
Input (English): Despite its usefulness, linked entities extracted from ELS's have issues because of low precision rates BIBREF11 and design challenges in training datasets BIBREF12 . First, the extracted entities may be ambiguous. Second, the linked entities may also be too common to be considered an entity.  
 Question: Why are current ELS's not sufficiently effective?
Output (English): Linked entities may be ambiguous or too common