Input: Read this: Several hundred pro-Tibet protesters gathered at the Trocadero with banners and Tibetan flags, and remained there for a peaceful protest, never approaching the torch relay itself. Among them was Jane Birkin, who spoke to the media about the "lack of freedom of speech" in China. Also present was Thupten Gyatso, President of the French Tibetan community, who called upon pro-Tibet demonstrators to "remain calm, non-violent, peaceful".
Question: Where did hundreds of pro-Tibet protesters meet?

Output: the Trocadero

Input: Read this: Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials. While the metal itself is radioactive, its high density makes it more effective than lead in halting radiation from strong sources such as radium. Other uses of depleted uranium include counterweights for aircraft control surfaces, as ballast for missile re-entry vehicles and as a shielding material. Due to its high density, this material is found in inertial guidance systems and in gyroscopic compasses. Depleted uranium is preferred over similarly dense metals due to its ability to be easily machined and cast as well as its relatively low cost. The main risk of exposure to depleted uranium is chemical poisoning by uranium oxide rather than radioactivity (uranium being only a weak alpha emitter).
Question: What is a strong source of radiation that is blocked by depleted uranium?

Output: radium

Input: Read this: At the end of November, Chopin returned to Paris. He passed the winter in unremitting illness, but gave occasional lessons and was visited by friends, including Delacroix and Franchomme. Occasionally he played, or accompanied the singing of Delfina Potocka, for his friends. During the summer of 1849, his friends found him an apartment in Chaillot, out of the centre of the city, for which the rent was secretly subsidised by an admirer, Princess Obreskoff. Here in June 1849 he was visited by Jenny Lind.
Question: Who did Chopin play for while she sang?

Output: Delfina Potocka

Input: Read this: Expansion caused controversy about Yale's new roles. Noah Porter, moral philosopher, was president from 1871 to 1886. During an age of tremendous expansion in higher education, Porter resisted the rise of the new research university, claiming that an eager embrace of its ideals would corrupt undergraduate education. Many of Porter's contemporaries criticized his administration, and historians since have disparaged his leadership. Levesque argues Porter was not a simple-minded reactionary, uncritically committed to tradition, but a principled and selective conservative. He did not endorse everything old or reject everything new; rather, he sought to apply long-established ethical and pedagogical principles to a rapidly changing culture. He may have misunderstood some of the challenges of his time, but he correctly anticipated the enduring tensions that have accompanied the emergence and growth of the modern university.
Question: When was Noah Porter vice president of Yale?

Output:
unanswerable