Definition: In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
Input: Passage: After their flight is cancelled due to stormy weather, neurosurgeon Dr. Ben Bass and photojournalist Alex Martin hire private pilot Walter to get them to Denver for connecting flights to Alex's wedding in New York and Ben's emergency surgery appointment in Baltimore. Walter, who has not filed a flight plan, suffers a fatal stroke mid-flight, and the plane crashes on a mountaintop in the High Uintas Wilderness. Ben, Alex, and Walter's dog survive the crash with various injuries.
Alex thinks Ben has a better chance of finding help if he leaves her behind, but Ben refuses. Stranded for days with dwindling supplies, Alex grows skeptical that they will be rescued, although Ben wants to wait for help by the plane's wreckage. After arguing, Alex starts a lone descent down the mountain. Ben catches up and they make-up over past grievances. 
Alex falls into freezing water near an abandoned cabin. They stay there for several days while Alex recuperates, and they have sex. Ben reveals that his wife died two years prior from a brain tumor. As Ben sleeps, Alex takes his picture. Later, she again asks Ben to leave her behind to find help. Ben initially agrees but soon returns; they press forward again. 
The dog alerts them to a nearby timber yard. On their way toward it, Ben's leg gets caught in a bear trap. Alex cannot free him, but she reaches the yard and collapses in front of an approaching truck. Ben awakens in a hospital and goes to Alex's room, where he finds her with Mark, her fiancé. After a brief discussion, Ben leaves heartbroken. Some time after, Mark discovers Alex is no longer in love with him.
Output:
What are the full names of the people that the dog alerts about a nearby timber yard?