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.

Sentence: There is a gap in the wall. You can see the garden behind it .
 Question: Why does the 'it' refer to the wall?
Because there is gap garden behind.

Sentence: The drain is clogged with hair. It has to be cleaned.
 Question: Why does the 'It' refer to the drain?
Because a drain with hair should be cleaned.

Sentence: Paul tried to call George on the phone, but he wasn't available.
 Question: Why does the 'he' refer to george?

Because George is the one being called, Paul is, of course, always available to himself.