You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
You need to read the given sentence and construct a question about the information present in the sentence. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is unique. The question must involve coreference resolution which is a task of clustering mentions in text that refer to the same underlying real world entities. For example let's take a sentence 'I voted for Obama because he was most aligned with my values, she said.' Here in this example 'I', 'my', and 'she' belong to the same cluster and 'Obama' and 'he' belong to the same cluster. Now let's discuss another example , original sentence: 'I voted for Trump because he was most aligned with my values',John said. Now here is the same sentence with resolved coreferences: 'John voted for Trump because Trump was most aligned with John's values',John said.

Sentence: I was trying to open the lock with the key, but someone had filled the keyhole with chewing gum, and I couldn't get it out.
Solution: What couldn't I get out?
Why? This question is based on the following sentence given- I was trying to open the lock with the key, but someone had filled the keyhole with chewing gum, and I couldn't get it out. From here it's clear that I couldn't get it out chewing gum and this is a good question since answer for this question is there in the sentence given.

New input: Sentence: Patting her back, the woman smiled at the girl.
Solution:
Whose back was the woman patting?