In this task you need to give reasons to justify the pronoun coreference relations. Each of the provided inputs contains a sentence with a target pronoun and a question about how to justify the coreference between a noun phrase and the target pronoun. Good practices involve the discussion about how the descriptions attached to the targeted pronoun relate to the noun phrase candidate in the question. The reasoning could come from one or multiple following knowledge types about commonsense: First: 'Property', the knowledge about property of objects (e.g., ice is cold). Second: 'Object', the knowledge about objects (e.g., cats have ears). Third: 'Eventuality', the knowledge about eventuality (e.g., 'wake up' happens before 'open eyes'). Forth: 'Spatial', the knowledge about spatial position (e.g., object at the back can be blocked). Fifth: 'Quantity', the knowledge about numbers (e.g., 2 is smaller than 10). Sixth: all other knowledge if above ones are not suitable. Write the sentence in natural language.

[Q]: Sentence: The sack of potatoes had been placed below the bag of flour, so it had to be moved first.
 Question: Why does the 'it' refer to the bag of flour?
[A]: Because the flour is on top, and the subject is the potatoes, which is the item wanted here.


[Q]: Sentence: I poured water from the bottle into the cup until it was empty.
 Question: Why does the 'it' refer to the bottle?
[A]: Because The bottle was empty.


[Q]: Sentence: Sam Goodman's biography of the Spartan general Xenophanes conveys a vivid sense of the difficulties he faced in his research.
 Question: Why does the 'he' refer to goodman?
[A]:
Because general Xenophanes conveys a vivid sense of the difficulties he faced in his research but Sam Goodman's biography of the Spartan.