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.
Example: Passage: Nearing London, Oliver encounters Jack Dawkins, a pickpocket more commonly known by the nickname the "Artful Dodger", and his sidekick, a boy of a humorous nature named Charley Bates, but Oliver's innocent and trusting nature fails to see any dishonesty in their actions. The Dodger provides Oliver with a free meal and tells him of a gentleman in London who will "give him lodgings for nothing, and never ask for change". Grateful for the unexpected assistance, Oliver follows the Dodger to the "old gentleman's" residence. In this way Oliver unwittingly falls in with an infamous Jewish criminal known as Fagin, the gentleman of whom the Artful Dodger spoke. Ensnared, Oliver lives with Fagin and his gang of juvenile pickpockets in their lair at Saffron Hill for some time, unaware of their criminal occupations. He believes they make wallets and handkerchiefs.
Example solution: Who believes Fagin's gang make wallets and handkerchiefs?.
Example explanation: This question is based on the following sentence in the passage "He believes they make wallets and handkerchiefs". It evaluates the understanding that the pronoun "he" refers to name "Oliver". You can ask questions like this one about most pronouns in a paragraph.

Problem: Passage: As the North Tower collapsed on September 11, 2001, heavy debris hit 7 World Trade Center, damaging the south face of the building and starting fires that continued to burn throughout the afternoon. The collapse also caused damage to the southwest corner between Floors 7 and 17 and on the south face between Floor 44 and the roof; other possible structural damage included a large vertical gash near the center of the south face between Floors 24 and 41. The building was equipped with a sprinkler system, but had many single-point vulnerabilities for failure: the sprinkler system required manual initiation of the electrical fire pumps, rather than being a fully automatic system; the floor-level controls had a single connection to the sprinkler water riser; and the sprinkler system required some power for the fire pump to deliver water. Additionally, water pressure was low, with little or no water to feed sprinklers.After the North Tower collapsed, some firefighters entered 7 World Trade Center to search the building. They attempted to extinguish small pockets of fire, but low water pressure hindered their efforts. Over the course of the day, fires burned out of control on several floors of 7 World Trade Center, the flames visible on the east side of the building. During the afternoon, the fire was also seen on floors 6–10, 13–14, 19–22, and 29–30. In particular, the fires on floors 7 through 9 and 11 through 13 continued to burn out of control during the afternoon. At approximately 2:00 pm, firefighters noticed a bulge in the southwest corner of 7 World Trade Center between the 10th and 13th floors, a sign that the building was unstable and might collapse. During the afternoon, firefighters also heard creaking sounds coming from the building. Around 3:30 pm, FDNY Chief Daniel A. Nigro decided to halt rescue operations, surface removal, and searches along the surface of the debris near 7 World Trade Center and evacuate the area due to concerns for the safety of personnel. The fire expanded the girders of the building, causing some to lose their structural integrity. This led column number 79, a critical column supporting a large part of the 13th floor, to buckle, causing the floors above it to collapse to the fifth floor; however, this could not be seen from outside the building. The structure also developed cracks in the facade just before the entire building started to fall. According to FEMA, this collapse started at 5:20:33 pm EDT when the east mechanical penthouse started crumbling. Differing times are given as to what time the building completely collapsed: at 5:21:10 pm EDT according to FEMA, and at 5:20:52 pm EDT according to NIST. There were no casualties associated with the collapse. NIST found no evidence to support conspiracy theories such as the collapse being the result of explosives; it found that a combination of factors including physical damage, fire and the building's unusual construction set off a chain-reaction collapse.
Solution: What was the last name of the person who halt rescue operations in 7 World Trade Center?