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 input: 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 output: 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.
Q: Passage: Churchill's study, on the first floor, was his "workshop for over 40 years" and "the heart of Chartwell".
In the 1920s, as Chancellor of the Exchequer, he planned his budgets in the room; in the 1930s, in isolation, he composed his speeches that warned against the rise of Hitler and dictated the books and articles that paid the bills; in 1945, defeated, he retreated here to write his histories; and here, in final retirement, he passed much of his old age. Throughout the 1930s, the study was his base for the writing of many of his most successful books. His biography of his ancestor Marlborough and his The World Crisis were written there, and A History of the English-Speaking Peoples was begun and concluded there, although interrupted by the Second World War. He also wrote many of his pre-war speeches in the study, although the house was less used during the war itself. Tilden exposed the early roof beams by removing the late-Victorian ceiling and inserted a Tudor doorcase. From the beams hang three banners, Churchill's standards as Knight of the Garter and Lord Warden of the Cinque Ports and the Union Flag raised over Rome on the night of 5 June 1944, the first British flag to fly over a liberated capital. The latter was a gift from Lord Alexander of Tunis. The study also contains portraits of Churchill's parents, Lord Randolph Churchill and Lady Randolph Churchill, the latter by John Singer Sargent. The floor is covered with a Khorassan carpet, a 69th birthday gift to Churchill from the Shah of Iran at the Teheran Conference in 1943.Beyond the study are Churchill's bedroom and his ensuite bathroom, with sunken bath. At the time of the house's opening to the public in 1966, these rooms were not made accessible, at the request of Churchill's family but, shortly before her death in 2014, Churchill's daughter Mary gave permission for their opening, and the Trust plans to make them accessible by 2020.
A:
What person did Churchill warn against?